Removed pickling of closed files as it doesn't work with py3 and was strange anyway

.gitignore

@@ -59,3 +59,6 @@ target/
 # IPython
 .ipynb_checkpoints
 Untitled.ipynb
+
+# Dev tools
+.idea

cloudpickle/cloudpickle.py

@@ -541,30 +541,27 @@ def save_file(self, obj):
             return self.save_reduce(getattr, (sys,'stderr'), obj=obj)
         if obj is sys.stdin:
             raise pickle.PicklingError("Cannot pickle standard input")
-        if not obj.closed:
-            if hasattr(obj, 'isatty') and obj.isatty():
-                raise pickle.PicklingError("Cannot pickle files that map to tty objects")
-            if 'r' not in obj.mode and '+' not in obj.mode:
-                raise pickle.PicklingError("Cannot pickle files that are not opened for reading: %s" % obj.mode)
+        if obj.closed:
+            raise pickle.PicklingError("Cannot pickle closed files")
+        if hasattr(obj, 'isatty') and obj.isatty():
+            raise pickle.PicklingError("Cannot pickle files that map to tty objects")
+        if 'r' not in obj.mode and '+' not in obj.mode:
+            raise pickle.PicklingError("Cannot pickle files that are not opened for reading: %s" % obj.mode)
 
         name = obj.name
 
         retval = pystringIO.StringIO()
 
-        if obj.closed:
-            #create an empty closed string io
-            retval.close()
-        else:
-            try:
-                # Read the whole file
-                curloc = obj.tell()
-                obj.seek(0)
-                contents = obj.read()
-                obj.seek(curloc)
-            except IOError:
-                raise pickle.PicklingError("Cannot pickle file %s as it cannot be read" % name)
-            retval.write(contents)
-            retval.seek(curloc)
+        try:
+            # Read the whole file
+            curloc = obj.tell()
+            obj.seek(0)
+            contents = obj.read()
+            obj.seek(curloc)
+        except IOError:
+            raise pickle.PicklingError("Cannot pickle file %s as it cannot be read" % name)
+        retval.write(contents)
+        retval.seek(curloc)
 
         retval.name = name
         self.save(retval)

tests/cloudpickle_file_test.py

@@ -35,17 +35,13 @@ def test_empty_file(self):
             self.assertEquals('', pickle.loads(cloudpickle.dumps(f)).read())
         os.remove(self.tmpfilepath)
 
-    # XXX: investigate why this is a problem under Python 3
-    @pytest.mark.skipif(sys.version_info > (2, 7),
-                        reason="only works on Python 2.x")
     def test_closed_file(self):
         # Write & close
         with open(self.tmpfilepath, 'w') as f:
             f.write(self.teststring)
-        # Cloudpickle returns an empty (& closed!) StringIO if the file was
-        # closed...
-        unpickled = pickle.loads(cloudpickle.dumps(f))
-        self.assertTrue(unpickled.closed)
+        with pytest.raises(pickle.PicklingError) as excinfo:
+            cloudpickle.dumps(f)
+        assert "Cannot pickle closed files" in str(excinfo.value)
         os.remove(self.tmpfilepath)
 
     def test_r_mode(self):