From 2ff5d7ca7e6d9ee13cda08467e29a00c5812ae80 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Thu, 6 Oct 2016 23:27:39 -0600
Subject: [PATCH 01/18] Add _PyImport_GetModuleDict().

---
 Include/import.h |  3 +++
 Python/import.c  | 22 ++++++++++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/Include/import.h b/Include/import.h
index 7e83985b3a43c6..00bf43454cc292 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -38,6 +38,9 @@ PyAPI_FUNC(PyObject *) PyImport_ExecCodeModuleObject(
     );
 #endif
 PyAPI_FUNC(PyObject *) PyImport_GetModuleDict(void);
+#ifndef Py_LIMITED_API
+PyAPI_FUNC(PyObject *) _PyImport_GetModuleDict(PyThreadState *tstate);
+#endif
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
 PyAPI_FUNC(PyObject *) PyImport_AddModuleObject(
     PyObject *name
diff --git a/Python/import.c b/Python/import.c
index 2aacf659351bb6..242e2547a15555 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -288,12 +288,30 @@ _PyImport_Fini(void)
 /* Helper for sys */
 
 PyObject *
-PyImport_GetModuleDict(void)
+_PyImport_GetModuleDict(PyThreadState *tstate)
 {
-    PyInterpreterState *interp = PyThreadState_GET()->interp;
+    PyInterpreterState *interp = tstate->interp;
     if (interp->modules == NULL)
         Py_FatalError("PyImport_GetModuleDict: no module dictionary!");
     return interp->modules;
+
+    /* We aren't ready to do this yet.
+    if (tstate->interp->sysdict == NULL)
+        Py_FatalError("_PyImport_GetModuleDict: no sys module!");
+
+    _Py_IDENTIFIER(modules);
+    PyObject *modules = _PyDict_GetItemId(tstate->interp->sysdict,
+                                          &PyId_modules);
+    if (modules == NULL)
+        Py_FatalError("lost sys.modules");
+    return modules;
+    */
+}
+
+PyObject *
+PyImport_GetModuleDict(void)
+{
+    return _PyImport_GetModuleDict(PyThreadState_GET());
 }
 
 

From 79a84612247ddbf11b0c91fc03cd2c29a704e657 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 10 Oct 2016 12:11:52 -0600
Subject: [PATCH 02/18] Import the sys module before any other imports.

---
 Python/pylifecycle.c | 51 ++++++++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 23 deletions(-)

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 0700569ac5affa..152b39d2321d4c 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -675,9 +675,20 @@ void _Py_InitializeCore(const _PyCoreConfig *config)
     if (!_PyFloat_Init())
         Py_FatalError("Py_InitializeCore: can't init float");
 
-    interp->modules = PyDict_New();
-    if (interp->modules == NULL)
+    PyObject *modules = PyDict_New();
+    if (modules == NULL)
         Py_FatalError("Py_InitializeCore: can't make modules dictionary");
+    interp->modules = modules;
+
+    sysmod = _PySys_BeginInit();
+    if (sysmod == NULL)
+        Py_FatalError("Py_InitializeCore: can't initialize sys");
+    interp->sysdict = PyModule_GetDict(sysmod);
+    if (interp->sysdict == NULL)
+        Py_FatalError("Py_InitializeCore: can't initialize sys dict");
+    Py_INCREF(interp->sysdict);
+    PyDict_SetItemString(interp->sysdict, "modules", modules);
+    _PyImport_FixupBuiltin(sysmod, "sys");
 
     /* Init Unicode implementation; relies on the codec registry */
     if (_PyUnicode_Init() < 0)
@@ -698,17 +709,6 @@ void _Py_InitializeCore(const _PyCoreConfig *config)
     /* initialize builtin exceptions */
     _PyExc_Init(bimod);
 
-    sysmod = _PySys_BeginInit();
-    if (sysmod == NULL)
-        Py_FatalError("Py_InitializeCore: can't initialize sys");
-    interp->sysdict = PyModule_GetDict(sysmod);
-    if (interp->sysdict == NULL)
-        Py_FatalError("Py_InitializeCore: can't initialize sys dict");
-    Py_INCREF(interp->sysdict);
-    _PyImport_FixupBuiltin(sysmod, "sys");
-    PyDict_SetItemString(interp->sysdict, "modules",
-                         interp->modules);
-
     /* Set up a preliminary stderr printer until we have enough
        infrastructure for the io module in place. */
     pstderr = PyFile_NewStdPrinter(fileno(stderr));
@@ -1203,7 +1203,21 @@ Py_NewInterpreter(void)
 
     /* XXX The following is lax in error checking */
 
-    interp->modules = PyDict_New();
+    PyObject *modules = PyDict_New();
+    if (modules == NULL)
+        Py_FatalError("Py_NewInterpreter: can't make modules dictionary");
+    interp->modules = modules;
+
+    sysmod = _PyImport_FindBuiltin("sys");
+    if (sysmod != NULL) {
+        interp->sysdict = PyModule_GetDict(sysmod);
+        if (interp->sysdict == NULL)
+            goto handle_error;
+        Py_INCREF(interp->sysdict);
+        PyDict_SetItemString(interp->sysdict, "modules", modules);
+        PySys_SetPath(Py_GetPath());
+        _PySys_EndInit(interp->sysdict);
+    }
 
     bimod = _PyImport_FindBuiltin("builtins");
     if (bimod != NULL) {
@@ -1216,18 +1230,9 @@ Py_NewInterpreter(void)
     /* initialize builtin exceptions */
     _PyExc_Init(bimod);
 
-    sysmod = _PyImport_FindBuiltin("sys");
     if (bimod != NULL && sysmod != NULL) {
         PyObject *pstderr;
 
-        interp->sysdict = PyModule_GetDict(sysmod);
-        if (interp->sysdict == NULL)
-            goto handle_error;
-        Py_INCREF(interp->sysdict);
-        _PySys_EndInit(interp->sysdict);
-        PySys_SetPath(Py_GetPath());
-        PyDict_SetItemString(interp->sysdict, "modules",
-                             interp->modules);
         /* Set up a preliminary stderr printer until we have enough
            infrastructure for the io module in place. */
         pstderr = PyFile_NewStdPrinter(fileno(stderr));

From 6f96d3a673f5a4d291c5d70c1654506a16a20e5d Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 10 Oct 2016 13:01:59 -0600
Subject: [PATCH 03/18] Pass the modules dict to _PyImport_FindBuiltin().

---
 Include/import.h     |  8 +++++++-
 Python/import.c      | 24 +++++++++++++++++++-----
 Python/pylifecycle.c |  4 ++--
 3 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/Include/import.h b/Include/import.h
index 00bf43454cc292..2501ec96453e0b 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -46,6 +46,9 @@ PyAPI_FUNC(PyObject *) PyImport_AddModuleObject(
     PyObject *name
     );
 #endif
+#ifndef Py_LIMITED_API
+PyAPI_FUNC(PyObject *) _PyImport_AddModuleObject(PyObject *, PyObject *);
+#endif
 PyAPI_FUNC(PyObject *) PyImport_AddModule(
     const char *name            /* UTF-8 encoded string */
     );
@@ -95,9 +98,12 @@ PyAPI_FUNC(int) _PyImport_ReleaseLock(void);
 PyAPI_FUNC(void) _PyImport_ReInitLock(void);
 
 PyAPI_FUNC(PyObject *) _PyImport_FindBuiltin(
-    const char *name            /* UTF-8 encoded string */
+    const char *name,            /* UTF-8 encoded string */
+    PyObject *modules
     );
 PyAPI_FUNC(PyObject *) _PyImport_FindExtensionObject(PyObject *, PyObject *);
+PyAPI_FUNC(PyObject *) _PyImport_FindExtensionObjectEx(PyObject *, PyObject *,
+                                                       PyObject *);
 PyAPI_FUNC(int) _PyImport_FixupBuiltin(
     PyObject *mod,
     const char *name            /* UTF-8 encoded string */
diff --git a/Python/import.c b/Python/import.c
index 242e2547a15555..994690ac2eca67 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -594,6 +594,14 @@ _PyImport_FixupBuiltin(PyObject *mod, const char *name)
 
 PyObject *
 _PyImport_FindExtensionObject(PyObject *name, PyObject *filename)
+{
+    PyObject *modules = PyImport_GetModuleDict();
+    return _PyImport_FindExtensionObjectEx(name, filename, modules);
+}
+
+PyObject *
+_PyImport_FindExtensionObjectEx(PyObject *name, PyObject *filename,
+                                PyObject *modules)
 {
     PyObject *mod, *mdict, *key;
     PyModuleDef* def;
@@ -610,7 +618,7 @@ _PyImport_FindExtensionObject(PyObject *name, PyObject *filename)
         /* Module does not support repeated initialization */
         if (def->m_base.m_copy == NULL)
             return NULL;
-        mod = PyImport_AddModuleObject(name);
+        mod = _PyImport_AddModuleObject(name, modules);
         if (mod == NULL)
             return NULL;
         mdict = PyModule_GetDict(mod);
@@ -625,14 +633,14 @@ _PyImport_FindExtensionObject(PyObject *name, PyObject *filename)
         mod = def->m_base.m_init();
         if (mod == NULL)
             return NULL;
-        if (PyDict_SetItem(PyImport_GetModuleDict(), name, mod) == -1) {
+        if (PyDict_SetItem(modules, name, mod) == -1) {
             Py_DECREF(mod);
             return NULL;
         }
         Py_DECREF(mod);
     }
     if (_PyState_AddModule(mod, def) < 0) {
-        PyDict_DelItem(PyImport_GetModuleDict(), name);
+        PyDict_DelItem(modules, name);
         Py_DECREF(mod);
         return NULL;
     }
@@ -644,13 +652,13 @@ _PyImport_FindExtensionObject(PyObject *name, PyObject *filename)
 }
 
 PyObject *
-_PyImport_FindBuiltin(const char *name)
+_PyImport_FindBuiltin(const char *name, PyObject *modules)
 {
     PyObject *res, *nameobj;
     nameobj = PyUnicode_InternFromString(name);
     if (nameobj == NULL)
         return NULL;
-    res = _PyImport_FindExtensionObject(nameobj, nameobj);
+    res = _PyImport_FindExtensionObjectEx(nameobj, nameobj, modules);
     Py_DECREF(nameobj);
     return res;
 }
@@ -665,6 +673,12 @@ PyObject *
 PyImport_AddModuleObject(PyObject *name)
 {
     PyObject *modules = PyImport_GetModuleDict();
+    return _PyImport_AddModuleObject(name, modules);
+}
+
+PyObject *
+_PyImport_AddModuleObject(PyObject *name, PyObject *modules)
+{
     PyObject *m;
 
     if ((m = PyDict_GetItemWithError(modules, name)) != NULL &&
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 152b39d2321d4c..bad6c269c69145 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1208,7 +1208,7 @@ Py_NewInterpreter(void)
         Py_FatalError("Py_NewInterpreter: can't make modules dictionary");
     interp->modules = modules;
 
-    sysmod = _PyImport_FindBuiltin("sys");
+    sysmod = _PyImport_FindBuiltin("sys", modules);
     if (sysmod != NULL) {
         interp->sysdict = PyModule_GetDict(sysmod);
         if (interp->sysdict == NULL)
@@ -1219,7 +1219,7 @@ Py_NewInterpreter(void)
         _PySys_EndInit(interp->sysdict);
     }
 
-    bimod = _PyImport_FindBuiltin("builtins");
+    bimod = _PyImport_FindBuiltin("builtins", modules);
     if (bimod != NULL) {
         interp->builtins = PyModule_GetDict(bimod);
         if (interp->builtins == NULL)

From ad8c082fa07bca377a5ea646bdaab17837bd5bb4 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Fri, 7 Oct 2016 00:02:53 -0600
Subject: [PATCH 04/18] Replace usage of interp->modules with
 PyImport_GetModuleDict().

---
 Objects/typeobject.c | 4 ++--
 Python/import.c      | 8 +++++---
 Python/pylifecycle.c | 5 ++---
 Python/sysmodule.c   | 5 +++--
 4 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index dc4d2edc5cf622..9ebbb21ef8d37d 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -3902,7 +3902,6 @@ import_copyreg(void)
 {
     PyObject *copyreg_str;
     PyObject *copyreg_module;
-    PyInterpreterState *interp = PyThreadState_GET()->interp;
     _Py_IDENTIFIER(copyreg);
 
     copyreg_str = _PyUnicode_FromId(&PyId_copyreg);
@@ -3914,7 +3913,8 @@ import_copyreg(void)
        by storing a reference to the cached module in a static variable, but
        this broke when multiple embedded interpreters were in use (see issue
        #17408 and #19088). */
-    copyreg_module = PyDict_GetItemWithError(interp->modules, copyreg_str);
+    PyObject *modules = PyImport_GetModuleDict();
+    copyreg_module = PyDict_GetItemWithError(modules, copyreg_str);
     if (copyreg_module != NULL) {
         Py_INCREF(copyreg_module);
         return copyreg_module;
diff --git a/Python/import.c b/Python/import.c
index 994690ac2eca67..4f4f76df733338 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -341,7 +341,7 @@ PyImport_Cleanup(void)
     Py_ssize_t pos;
     PyObject *key, *value, *dict;
     PyInterpreterState *interp = PyThreadState_GET()->interp;
-    PyObject *modules = interp->modules;
+    PyObject *modules = PyImport_GetModuleDict();
     PyObject *weaklist = NULL;
     const char * const *p;
 
@@ -1543,7 +1543,8 @@ PyImport_ImportModuleLevelObject(PyObject *name, PyObject *globals,
         Py_INCREF(abs_name);
     }
 
-    mod = PyDict_GetItem(interp->modules, abs_name);
+    PyObject *modules = PyImport_GetModuleDict();
+    mod = PyDict_GetItem(modules, abs_name);
     if (mod != NULL && mod != Py_None) {
         _Py_IDENTIFIER(__spec__);
         _Py_IDENTIFIER(_initializing);
@@ -1630,7 +1631,8 @@ PyImport_ImportModuleLevelObject(PyObject *name, PyObject *globals,
                     goto error;
                 }
 
-                final_mod = PyDict_GetItem(interp->modules, to_return);
+                PyObject *modules = PyImport_GetModuleDict();
+                final_mod = PyDict_GetItem(modules, to_return);
                 Py_DECREF(to_return);
                 if (final_mod == NULL) {
                     PyErr_Format(PyExc_KeyError,
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index bad6c269c69145..789d82f5eb747e 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1908,9 +1908,8 @@ wait_for_thread_shutdown(void)
 {
     _Py_IDENTIFIER(_shutdown);
     PyObject *result;
-    PyThreadState *tstate = PyThreadState_GET();
-    PyObject *threading = PyMapping_GetItemString(tstate->interp->modules,
-                                                  "threading");
+    PyObject *modules = PyImport_GetModuleDict();
+    PyObject *threading = PyMapping_GetItemString(modules, "threading");
     if (threading == NULL) {
         /* threading not imported */
         PyErr_Clear();
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index dd127a1f7ce003..e0bed71bc35036 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -160,8 +160,9 @@ static PyObject *
 sys_displayhook(PyObject *self, PyObject *o)
 {
     PyObject *outf;
-    PyInterpreterState *interp = PyThreadState_GET()->interp;
-    PyObject *modules = interp->modules;
+    PyObject *modules = PyImport_GetModuleDict();
+    if (modules == NULL)
+        return NULL;
     PyObject *builtins;
     static PyObject *newline = NULL;
     int err;

From 12f55d30be0a66760cb0806e06093e08f43c60da Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 10 Oct 2016 11:23:44 -0600
Subject: [PATCH 05/18] Add _PyImport_EnsureInitialized().

---
 Include/import.h |  1 +
 Python/import.c  | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/Include/import.h b/Include/import.h
index 2501ec96453e0b..e71888ed91a19c 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -40,6 +40,7 @@ PyAPI_FUNC(PyObject *) PyImport_ExecCodeModuleObject(
 PyAPI_FUNC(PyObject *) PyImport_GetModuleDict(void);
 #ifndef Py_LIMITED_API
 PyAPI_FUNC(PyObject *) _PyImport_GetModuleDict(PyThreadState *tstate);
+PyAPI_FUNC(void) _PyImport_EnsureInitialized(PyInterpreterState *interp);
 #endif
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
 PyAPI_FUNC(PyObject *) PyImport_AddModuleObject(
diff --git a/Python/import.c b/Python/import.c
index 4f4f76df733338..8e29085ab1f585 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -314,6 +314,21 @@ PyImport_GetModuleDict(void)
     return _PyImport_GetModuleDict(PyThreadState_GET());
 }
 
+/* In some corner cases it is important to be sure that the import
+   machinery has been initialized (or not cleaned up yet).  For
+   example, see issue #4236 and PyModule_Create2(). */
+
+void
+_PyImport_EnsureInitialized(PyInterpreterState *interp)
+{
+    if (interp->modules == NULL)
+        goto notinitialized;
+    return;
+
+notinitialized:
+    Py_FatalError("Python import machinery not initialized");
+}
+
 
 /* List of names to clear in sys */
 static const char * const sys_deletes[] = {

From eb2d6f980179a61b7b667b3dafc13a591e3efef1 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 10 Oct 2016 11:30:02 -0600
Subject: [PATCH 06/18] Add _PyModule_Create2().

---
 Include/modsupport.h   |  4 ++++
 Objects/moduleobject.c | 11 ++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/Include/modsupport.h b/Include/modsupport.h
index 8c7cf39d9a3ea9..3ba15b7853d248 100644
--- a/Include/modsupport.h
+++ b/Include/modsupport.h
@@ -191,6 +191,10 @@ PyAPI_FUNC(int) PyModule_ExecDef(PyObject *module, PyModuleDef *def);
 
 PyAPI_FUNC(PyObject *) PyModule_Create2(struct PyModuleDef*,
                                      int apiver);
+#ifndef Py_LIMITED_API
+PyAPI_FUNC(PyObject *) _PyModule_Create2(struct PyModuleDef*,
+                                         int apiver);
+#endif
 
 #ifdef Py_LIMITED_API
 #define PyModule_Create(module) \
diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index 5fab06d31df036..17ee15782b23fa 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -161,12 +161,17 @@ _add_methods_to_object(PyObject *module, PyObject *name, PyMethodDef *functions)
 
 PyObject *
 PyModule_Create2(struct PyModuleDef* module, int module_api_version)
+{
+    _PyImport_EnsureInitialized(PyThreadState_GET()->interp);
+    return _PyModule_Create2(module, module_api_version);
+}
+
+PyObject *
+_PyModule_Create2(struct PyModuleDef* module, int module_api_version)
 {
     const char* name;
     PyModuleObject *m;
-    PyInterpreterState *interp = PyThreadState_Get()->interp;
-    if (interp->modules == NULL)
-        Py_FatalError("Python import machinery not initialized");
+
     if (!PyModuleDef_Init(module))
         return NULL;
     name = module->m_name;

From 6a04c1c2f68fe17b6c33a9274c26148d14106dab Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 10 Oct 2016 11:31:51 -0600
Subject: [PATCH 07/18] Use _PyModule_Create2() for key builtin modules.

---
 Python/bltinmodule.c | 2 +-
 Python/sysmodule.c   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 5e1f1d3854fc67..df84cf1c0d3c16 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -2685,7 +2685,7 @@ _PyBuiltin_Init(void)
         PyType_Ready(&PyZip_Type) < 0)
         return NULL;
 
-    mod = PyModule_Create(&builtinsmodule);
+    mod = _PyModule_Create2(&builtinsmodule, PYTHON_API_VERSION);
     if (mod == NULL)
         return NULL;
     dict = PyModule_GetDict(mod);
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index e0bed71bc35036..4827cf2413945d 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1940,7 +1940,7 @@ _PySys_BeginInit(void)
     PyObject *m, *sysdict, *version_info;
     int res;
 
-    m = PyModule_Create(&sysmodule);
+    m = _PyModule_Create2(&sysmodule, PYTHON_API_VERSION);
     if (m == NULL)
         return NULL;
     sysdict = PyModule_GetDict(m);

From 26bdb7e65ca9eb481af4801c4ca7880360495e25 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 10 Oct 2016 11:23:44 -0600
Subject: [PATCH 08/18] Check sys.modules in _PyImport_EnsureInitialized().

---
 Python/import.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Python/import.c b/Python/import.c
index 8e29085ab1f585..5cff558e0384e5 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -323,6 +323,14 @@ _PyImport_EnsureInitialized(PyInterpreterState *interp)
 {
     if (interp->modules == NULL)
         goto notinitialized;
+    /* We aren't ready to do this yet.
+    if (interp->sysdict == NULL)
+        goto notinitialized;
+    _Py_IDENTIFIER(modules);
+    PyObject *modules = _PyDict_GetItemId(interp->sysdict, &PyId_modules);
+    if (modules == NULL)
+        goto notinitialized;
+    */
     return;
 
 notinitialized:

From eac74033ee09643f6f1369fffe2eb30d148d0892 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 10 Oct 2016 13:55:55 -0600
Subject: [PATCH 09/18] Pass the modules dict to _PyImport_FixupBuiltin().

---
 Include/import.h     |  5 ++++-
 Python/import.c      | 15 +++++++++++----
 Python/pylifecycle.c |  4 ++--
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/Include/import.h b/Include/import.h
index e71888ed91a19c..a50b7fdd87abac 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -107,9 +107,12 @@ PyAPI_FUNC(PyObject *) _PyImport_FindExtensionObjectEx(PyObject *, PyObject *,
                                                        PyObject *);
 PyAPI_FUNC(int) _PyImport_FixupBuiltin(
     PyObject *mod,
-    const char *name            /* UTF-8 encoded string */
+    const char *name,            /* UTF-8 encoded string */
+    PyObject *modules
     );
 PyAPI_FUNC(int) _PyImport_FixupExtensionObject(PyObject*, PyObject *, PyObject *);
+PyAPI_FUNC(int) _PyImport_FixupExtensionObjectEx(PyObject*, PyObject *,
+                                                 PyObject *, PyObject *);
 
 struct _inittab {
     const char *name;           /* ASCII encoded string */
diff --git a/Python/import.c b/Python/import.c
index 5cff558e0384e5..69aac3b6084aea 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -554,7 +554,15 @@ int
 _PyImport_FixupExtensionObject(PyObject *mod, PyObject *name,
                                PyObject *filename)
 {
-    PyObject *modules, *dict, *key;
+    PyObject *modules = PyImport_GetModuleDict();
+    return _PyImport_FixupExtensionObjectEx(mod, name, filename, modules);
+}
+
+int
+_PyImport_FixupExtensionObjectEx(PyObject *mod, PyObject *name,
+                                 PyObject *filename, PyObject *modules)
+{
+    PyObject *dict, *key;
     struct PyModuleDef *def;
     int res;
     if (extensions == NULL) {
@@ -571,7 +579,6 @@ _PyImport_FixupExtensionObject(PyObject *mod, PyObject *name,
         PyErr_BadInternalCall();
         return -1;
     }
-    modules = PyImport_GetModuleDict();
     if (PyDict_SetItem(modules, name, mod) < 0)
         return -1;
     if (_PyState_AddModule(mod, def) < 0) {
@@ -603,14 +610,14 @@ _PyImport_FixupExtensionObject(PyObject *mod, PyObject *name,
 }
 
 int
-_PyImport_FixupBuiltin(PyObject *mod, const char *name)
+_PyImport_FixupBuiltin(PyObject *mod, const char *name, PyObject *modules)
 {
     int res;
     PyObject *nameobj;
     nameobj = PyUnicode_InternFromString(name);
     if (nameobj == NULL)
         return -1;
-    res = _PyImport_FixupExtensionObject(mod, nameobj, nameobj);
+    res = _PyImport_FixupExtensionObjectEx(mod, nameobj, nameobj, modules);
     Py_DECREF(nameobj);
     return res;
 }
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 789d82f5eb747e..330fb634af6429 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -688,7 +688,7 @@ void _Py_InitializeCore(const _PyCoreConfig *config)
         Py_FatalError("Py_InitializeCore: can't initialize sys dict");
     Py_INCREF(interp->sysdict);
     PyDict_SetItemString(interp->sysdict, "modules", modules);
-    _PyImport_FixupBuiltin(sysmod, "sys");
+    _PyImport_FixupBuiltin(sysmod, "sys", modules);
 
     /* Init Unicode implementation; relies on the codec registry */
     if (_PyUnicode_Init() < 0)
@@ -700,7 +700,7 @@ void _Py_InitializeCore(const _PyCoreConfig *config)
     bimod = _PyBuiltin_Init();
     if (bimod == NULL)
         Py_FatalError("Py_InitializeCore: can't initialize builtins modules");
-    _PyImport_FixupBuiltin(bimod, "builtins");
+    _PyImport_FixupBuiltin(bimod, "builtins", modules);
     interp->builtins = PyModule_GetDict(bimod);
     if (interp->builtins == NULL)
         Py_FatalError("Py_InitializeCore: can't initialize builtins dict");

From 1166c57254c0fdda066e6b5ddc6a88e9696d707f Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Tue, 11 Oct 2016 17:00:32 -0600
Subject: [PATCH 10/18] Pass PyInterpreterState to _PyImport_GetModuleDict().

---
 Include/import.h |  4 ++--
 Python/import.c  | 12 +++++-------
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/Include/import.h b/Include/import.h
index a50b7fdd87abac..a8d74f2b913716 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -39,8 +39,8 @@ PyAPI_FUNC(PyObject *) PyImport_ExecCodeModuleObject(
 #endif
 PyAPI_FUNC(PyObject *) PyImport_GetModuleDict(void);
 #ifndef Py_LIMITED_API
-PyAPI_FUNC(PyObject *) _PyImport_GetModuleDict(PyThreadState *tstate);
-PyAPI_FUNC(void) _PyImport_EnsureInitialized(PyInterpreterState *interp);
+PyAPI_FUNC(PyObject *) _PyImport_GetModuleDict(PyInterpreterState *);
+PyAPI_FUNC(void) _PyImport_EnsureInitialized(PyInterpreterState *);
 #endif
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
 PyAPI_FUNC(PyObject *) PyImport_AddModuleObject(
diff --git a/Python/import.c b/Python/import.c
index 69aac3b6084aea..2016ce721fac0f 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -288,20 +288,18 @@ _PyImport_Fini(void)
 /* Helper for sys */
 
 PyObject *
-_PyImport_GetModuleDict(PyThreadState *tstate)
+_PyImport_GetModuleDict(PyInterpreterState *interp)
 {
-    PyInterpreterState *interp = tstate->interp;
     if (interp->modules == NULL)
         Py_FatalError("PyImport_GetModuleDict: no module dictionary!");
     return interp->modules;
 
     /* We aren't ready to do this yet.
-    if (tstate->interp->sysdict == NULL)
-        Py_FatalError("_PyImport_GetModuleDict: no sys module!");
+    if (interp->sysdict == NULL)
+        Py_FatalError("PyImport_GetModuleDict: no sys module!");
 
     _Py_IDENTIFIER(modules);
-    PyObject *modules = _PyDict_GetItemId(tstate->interp->sysdict,
-                                          &PyId_modules);
+    PyObject *modules = _PyDict_GetItemId(interp->sysdict, &PyId_modules);
     if (modules == NULL)
         Py_FatalError("lost sys.modules");
     return modules;
@@ -311,7 +309,7 @@ _PyImport_GetModuleDict(PyThreadState *tstate)
 PyObject *
 PyImport_GetModuleDict(void)
 {
-    return _PyImport_GetModuleDict(PyThreadState_GET());
+    return _PyImport_GetModuleDict(PyThreadState_GET()->interp);
 }
 
 /* In some corner cases it is important to be sure that the import

From da3ce95e65e39be547753f39ba262b043159c929 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Tue, 11 Oct 2016 17:04:30 -0600
Subject: [PATCH 11/18] Drop _PyImport_GetModuleDict().

---
 Include/import.h |  1 -
 Python/import.c  | 14 +++++---------
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/Include/import.h b/Include/import.h
index a8d74f2b913716..233697b89ebcb1 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -39,7 +39,6 @@ PyAPI_FUNC(PyObject *) PyImport_ExecCodeModuleObject(
 #endif
 PyAPI_FUNC(PyObject *) PyImport_GetModuleDict(void);
 #ifndef Py_LIMITED_API
-PyAPI_FUNC(PyObject *) _PyImport_GetModuleDict(PyInterpreterState *);
 PyAPI_FUNC(void) _PyImport_EnsureInitialized(PyInterpreterState *);
 #endif
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
diff --git a/Python/import.c b/Python/import.c
index 2016ce721fac0f..6db277e46a28e8 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -288,30 +288,26 @@ _PyImport_Fini(void)
 /* Helper for sys */
 
 PyObject *
-_PyImport_GetModuleDict(PyInterpreterState *interp)
+PyImport_GetModuleDict(void)
 {
+    PyInterpreterState *interp = PyThreadState_GET()->interp;
     if (interp->modules == NULL)
         Py_FatalError("PyImport_GetModuleDict: no module dictionary!");
     return interp->modules;
 
     /* We aren't ready to do this yet.
-    if (interp->sysdict == NULL)
+    PyObject *sysdict = PyThreadState_GET()->interp->sysdict;
+    if (sysdict == NULL)
         Py_FatalError("PyImport_GetModuleDict: no sys module!");
 
     _Py_IDENTIFIER(modules);
-    PyObject *modules = _PyDict_GetItemId(interp->sysdict, &PyId_modules);
+    PyObject *modules = _PyDict_GetItemId(sysdict, &PyId_modules);
     if (modules == NULL)
         Py_FatalError("lost sys.modules");
     return modules;
     */
 }
 
-PyObject *
-PyImport_GetModuleDict(void)
-{
-    return _PyImport_GetModuleDict(PyThreadState_GET()->interp);
-}
-
 /* In some corner cases it is important to be sure that the import
    machinery has been initialized (or not cleaned up yet).  For
    example, see issue #4236 and PyModule_Create2(). */

From ef17b812f0a0d06f84bb7edef148c52f769a110b Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Wed, 17 May 2017 16:55:14 -0700
Subject: [PATCH 12/18] _PyModule_Create2 -> _PyModule_CreateInitialized

---
 Include/modsupport.h   | 4 ++--
 Objects/moduleobject.c | 4 ++--
 Python/bltinmodule.c   | 2 +-
 Python/sysmodule.c     | 2 +-
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/Include/modsupport.h b/Include/modsupport.h
index 3ba15b7853d248..73d86a94b957f6 100644
--- a/Include/modsupport.h
+++ b/Include/modsupport.h
@@ -192,8 +192,8 @@ PyAPI_FUNC(int) PyModule_ExecDef(PyObject *module, PyModuleDef *def);
 PyAPI_FUNC(PyObject *) PyModule_Create2(struct PyModuleDef*,
                                      int apiver);
 #ifndef Py_LIMITED_API
-PyAPI_FUNC(PyObject *) _PyModule_Create2(struct PyModuleDef*,
-                                         int apiver);
+PyAPI_FUNC(PyObject *) _PyModule_CreateInitialized(struct PyModuleDef*,
+                                                   int apiver);
 #endif
 
 #ifdef Py_LIMITED_API
diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index 17ee15782b23fa..35916f32639ea8 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -163,11 +163,11 @@ PyObject *
 PyModule_Create2(struct PyModuleDef* module, int module_api_version)
 {
     _PyImport_EnsureInitialized(PyThreadState_GET()->interp);
-    return _PyModule_Create2(module, module_api_version);
+    return _PyModule_CreateInitialized(module, module_api_version);
 }
 
 PyObject *
-_PyModule_Create2(struct PyModuleDef* module, int module_api_version)
+_PyModule_CreateInitialized(struct PyModuleDef* module, int module_api_version)
 {
     const char* name;
     PyModuleObject *m;
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index df84cf1c0d3c16..c363cfe8cea26b 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -2685,7 +2685,7 @@ _PyBuiltin_Init(void)
         PyType_Ready(&PyZip_Type) < 0)
         return NULL;
 
-    mod = _PyModule_Create2(&builtinsmodule, PYTHON_API_VERSION);
+    mod = _PyModule_CreateInitialized(&builtinsmodule, PYTHON_API_VERSION);
     if (mod == NULL)
         return NULL;
     dict = PyModule_GetDict(mod);
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 4827cf2413945d..ff2f9aef92dc58 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1940,7 +1940,7 @@ _PySys_BeginInit(void)
     PyObject *m, *sysdict, *version_info;
     int res;
 
-    m = _PyModule_Create2(&sysmodule, PYTHON_API_VERSION);
+    m = _PyModule_CreateInitialized(&sysmodule, PYTHON_API_VERSION);
     if (m == NULL)
         return NULL;
     sysdict = PyModule_GetDict(m);

From a17d5ff9366aac6b5f2991e6b45968f6432595ac Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Wed, 17 May 2017 22:41:44 -0700
Subject: [PATCH 13/18] _PyImport_EnsureInitialized() ->
 _PyImport_IsInitialized()

---
 Include/import.h       |  2 +-
 Objects/moduleobject.c |  3 ++-
 Python/import.c        | 15 ++++++---------
 3 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/Include/import.h b/Include/import.h
index 233697b89ebcb1..ec20794c115afb 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -39,7 +39,7 @@ PyAPI_FUNC(PyObject *) PyImport_ExecCodeModuleObject(
 #endif
 PyAPI_FUNC(PyObject *) PyImport_GetModuleDict(void);
 #ifndef Py_LIMITED_API
-PyAPI_FUNC(void) _PyImport_EnsureInitialized(PyInterpreterState *);
+PyAPI_FUNC(int) _PyImport_IsInitialized(PyInterpreterState *);
 #endif
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03030000
 PyAPI_FUNC(PyObject *) PyImport_AddModuleObject(
diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index 35916f32639ea8..2be49fbda38908 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -162,7 +162,8 @@ _add_methods_to_object(PyObject *module, PyObject *name, PyMethodDef *functions)
 PyObject *
 PyModule_Create2(struct PyModuleDef* module, int module_api_version)
 {
-    _PyImport_EnsureInitialized(PyThreadState_GET()->interp);
+    if (!_PyImport_IsInitialized(PyThreadState_GET()->interp))
+        Py_FatalError("Python import machinery not initialized");
     return _PyModule_CreateInitialized(module, module_api_version);
 }
 
diff --git a/Python/import.c b/Python/import.c
index 6db277e46a28e8..79e54db6802f6f 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -312,23 +312,20 @@ PyImport_GetModuleDict(void)
    machinery has been initialized (or not cleaned up yet).  For
    example, see issue #4236 and PyModule_Create2(). */
 
-void
-_PyImport_EnsureInitialized(PyInterpreterState *interp)
+int
+_PyImport_IsInitialized(PyInterpreterState *interp)
 {
     if (interp->modules == NULL)
-        goto notinitialized;
+        return 0;
     /* We aren't ready to do this yet.
     if (interp->sysdict == NULL)
-        goto notinitialized;
+        return 0;
     _Py_IDENTIFIER(modules);
     PyObject *modules = _PyDict_GetItemId(interp->sysdict, &PyId_modules);
     if (modules == NULL)
-        goto notinitialized;
+        return 0;
     */
-    return;
-
-notinitialized:
-    Py_FatalError("Python import machinery not initialized");
+    return 1;
 }
 
 

From acc270b2c2b126d8e55f9029a308f6753a33c4b9 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 4 Sep 2017 10:46:53 -0700
Subject: [PATCH 14/18] Add a Misc/NEWS entry.

---
 .../Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst

diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst b/Misc/NEWS.d/next/Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst
new file mode 100644
index 00000000000000..0e5e5c837fe8ea
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst	
@@ -0,0 +1,3 @@
+``PyInterpreterState`` has a "modules" field that is copied into
+``sys.modules`` during interpreter startup.  We restructure code
+to better isolate sys.modules, to make it easier to sync them up.

From bc6a0f14b725590fc54ac02bb03f2e9823298b3e Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 4 Sep 2017 11:39:41 -0700
Subject: [PATCH 15/18] Fix style (bracket placement).

---
 Python/import.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Python/import.c b/Python/import.c
index 79e54db6802f6f..772603c3cb0feb 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -297,13 +297,15 @@ PyImport_GetModuleDict(void)
 
     /* We aren't ready to do this yet.
     PyObject *sysdict = PyThreadState_GET()->interp->sysdict;
-    if (sysdict == NULL)
+    if (sysdict == NULL) {
         Py_FatalError("PyImport_GetModuleDict: no sys module!");
+    }
 
     _Py_IDENTIFIER(modules);
     PyObject *modules = _PyDict_GetItemId(sysdict, &PyId_modules);
-    if (modules == NULL)
+    if (modules == NULL) {
         Py_FatalError("lost sys.modules");
+    }
     return modules;
     */
 }
@@ -328,7 +330,6 @@ _PyImport_IsInitialized(PyInterpreterState *interp)
     return 1;
 }
 
-
 /* List of names to clear in sys */
 static const char * const sys_deletes[] = {
     "path", "argv", "ps1", "ps2",

From c7a25242925afc5e6d9808463766cd8dfda22601 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Mon, 4 Sep 2017 13:19:52 -0700
Subject: [PATCH 16/18] Drop _PyImport_FixupExtensionObjectEx().

---
 Include/import.h  |  5 ++---
 Python/import.c   | 17 +++++++----------
 Python/importdl.c |  3 ++-
 3 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/Include/import.h b/Include/import.h
index ec20794c115afb..95c52b0bfba129 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -109,9 +109,8 @@ PyAPI_FUNC(int) _PyImport_FixupBuiltin(
     const char *name,            /* UTF-8 encoded string */
     PyObject *modules
     );
-PyAPI_FUNC(int) _PyImport_FixupExtensionObject(PyObject*, PyObject *, PyObject *);
-PyAPI_FUNC(int) _PyImport_FixupExtensionObjectEx(PyObject*, PyObject *,
-                                                 PyObject *, PyObject *);
+PyAPI_FUNC(int) _PyImport_FixupExtensionObject(PyObject*, PyObject *,
+                                               PyObject *, PyObject *);
 
 struct _inittab {
     const char *name;           /* ASCII encoded string */
diff --git a/Python/import.c b/Python/import.c
index 772603c3cb0feb..084895cef66420 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -544,14 +544,6 @@ PyImport_GetMagicTag(void)
 
 int
 _PyImport_FixupExtensionObject(PyObject *mod, PyObject *name,
-                               PyObject *filename)
-{
-    PyObject *modules = PyImport_GetModuleDict();
-    return _PyImport_FixupExtensionObjectEx(mod, name, filename, modules);
-}
-
-int
-_PyImport_FixupExtensionObjectEx(PyObject *mod, PyObject *name,
                                  PyObject *filename, PyObject *modules)
 {
     PyObject *dict, *key;
@@ -609,7 +601,7 @@ _PyImport_FixupBuiltin(PyObject *mod, const char *name, PyObject *modules)
     nameobj = PyUnicode_InternFromString(name);
     if (nameobj == NULL)
         return -1;
-    res = _PyImport_FixupExtensionObjectEx(mod, nameobj, nameobj, modules);
+    res = _PyImport_FixupExtensionObject(mod, nameobj, nameobj, modules);
     Py_DECREF(nameobj);
     return res;
 }
@@ -1096,6 +1088,7 @@ _imp_create_builtin(PyObject *module, PyObject *spec)
         return NULL;
     }
 
+    PyObject *modules = NULL;
     for (p = PyImport_Inittab; p->name != NULL; p++) {
         PyModuleDef *def;
         if (_PyUnicode_EqualToASCIIString(name, p->name)) {
@@ -1121,7 +1114,11 @@ _imp_create_builtin(PyObject *module, PyObject *spec)
                     return NULL;
                 }
                 def->m_base.m_init = p->initfunc;
-                if (_PyImport_FixupExtensionObject(mod, name, name) < 0) {
+                if (modules == NULL) {
+                    modules = PyImport_GetModuleDict();
+                }
+                if (_PyImport_FixupExtensionObject(mod, name, name,
+                                                   modules) < 0) {
                     Py_DECREF(name);
                     return NULL;
                 }
diff --git a/Python/importdl.c b/Python/importdl.c
index d8656b943336ec..32fb7e1be212ca 100644
--- a/Python/importdl.c
+++ b/Python/importdl.c
@@ -215,7 +215,8 @@ _PyImport_LoadDynamicModuleWithSpec(PyObject *spec, FILE *fp)
     else
         Py_INCREF(path);
 
-    if (_PyImport_FixupExtensionObject(m, name_unicode, path) < 0)
+    PyObject *modules = PyImport_GetModuleDict();
+    if (_PyImport_FixupExtensionObject(m, name_unicode, path, modules) < 0)
         goto error;
 
     Py_DECREF(name_unicode);

From aceaacda94c6a40a3952088664c4cc381ad4c374 Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Thu, 14 Sep 2017 15:24:38 +0000
Subject: [PATCH 17/18] Fix the NEWS entry.

---
 .../Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst | 3 ---
 .../Core and Builtins/2017-09-11-09-24-21.bpo-28411.12SpAm.rst | 3 +++
 2 files changed, 3 insertions(+), 3 deletions(-)
 delete mode 100644 Misc/NEWS.d/next/Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2017-09-11-09-24-21.bpo-28411.12SpAm.rst

diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst b/Misc/NEWS.d/next/Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst
deleted file mode 100644
index 0e5e5c837fe8ea..00000000000000
--- a/Misc/NEWS.d/next/Core and Builtins/2017-09-04-10-46-09.bpo-28411.IU9rQL.rst	
+++ /dev/null
@@ -1,3 +0,0 @@
-``PyInterpreterState`` has a "modules" field that is copied into
-``sys.modules`` during interpreter startup.  We restructure code
-to better isolate sys.modules, to make it easier to sync them up.
diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-09-11-09-24-21.bpo-28411.12SpAm.rst b/Misc/NEWS.d/next/Core and Builtins/2017-09-11-09-24-21.bpo-28411.12SpAm.rst
new file mode 100644
index 00000000000000..47f9fa684e5a5a
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2017-09-11-09-24-21.bpo-28411.12SpAm.rst	
@@ -0,0 +1,3 @@
+Change direct usage of PyInterpreterState.modules to PyImport_GetModuleDict().
+Also introduce more uniformity in other code that deals with sys.modules.
+This helps reduce complications when working on sys.modules.

From 5b87111ba5359c84e3d2a027e70212ac00ef073c Mon Sep 17 00:00:00 2001
From: Eric Snow <ericsnowcurrently@gmail.com>
Date: Thu, 14 Sep 2017 17:47:26 +0000
Subject: [PATCH 18/18] Drop commented-out code.

---
 Python/import.c | 22 ----------------------
 1 file changed, 22 deletions(-)

diff --git a/Python/import.c b/Python/import.c
index 084895cef66420..7aa7a1bdf7988e 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -294,20 +294,6 @@ PyImport_GetModuleDict(void)
     if (interp->modules == NULL)
         Py_FatalError("PyImport_GetModuleDict: no module dictionary!");
     return interp->modules;
-
-    /* We aren't ready to do this yet.
-    PyObject *sysdict = PyThreadState_GET()->interp->sysdict;
-    if (sysdict == NULL) {
-        Py_FatalError("PyImport_GetModuleDict: no sys module!");
-    }
-
-    _Py_IDENTIFIER(modules);
-    PyObject *modules = _PyDict_GetItemId(sysdict, &PyId_modules);
-    if (modules == NULL) {
-        Py_FatalError("lost sys.modules");
-    }
-    return modules;
-    */
 }
 
 /* In some corner cases it is important to be sure that the import
@@ -319,14 +305,6 @@ _PyImport_IsInitialized(PyInterpreterState *interp)
 {
     if (interp->modules == NULL)
         return 0;
-    /* We aren't ready to do this yet.
-    if (interp->sysdict == NULL)
-        return 0;
-    _Py_IDENTIFIER(modules);
-    PyObject *modules = _PyDict_GetItemId(interp->sysdict, &PyId_modules);
-    if (modules == NULL)
-        return 0;
-    */
     return 1;
 }