WIP for #9645 (gather opinions)

Author: nicoddemus

src/_pytest/pathlib.py

@@ -603,11 +603,14 @@ def insert_missing_modules(modules: Dict[str, ModuleType], module_name: str) ->
     module_parts = module_name.split(".")
     while module_name:
         if module_name not in modules:
-            module = ModuleType(
-                module_name,
-                doc="Empty module created by pytest's importmode=importlib.",
-            )
-            modules[module_name] = module
+            try:
+                __import__(module_name)
+            except ModuleNotFoundError:
+                module = ModuleType(
+                    module_name,
+                    doc="Empty module created by pytest's importmode=importlib.",
+                )
+                modules[module_name] = module
         module_parts.pop(-1)
         module_name = ".".join(module_parts)