diff -r ec00f8570c55 Python/import.c
--- a/Python/import.c	Mon Nov 05 22:23:16 2012 +0200
+++ b/Python/import.c	Tue Nov 06 15:41:51 2012 +0100
@@ -449,13 +449,13 @@
 
 /* Magic for extension modules (built-in as well as dynamically
    loaded).  To prevent initializing an extension module more than
-   once, we keep a static dictionary 'extensions' keyed by module name
-   (for built-in modules) or by filename (for dynamically loaded
-   modules), containing these modules.  A copy of the module's
-   dictionary is stored by calling _PyImport_FixupExtensionObject()
-   immediately after the module initialization function succeeds.  A
-   copy can be retrieved from there by calling
-   _PyImport_FindExtensionObject().
+   once, we keep a static dictionary 'extensions' keyed by the tuple
+        (module name, module name)  (for built-in modules) or by
+        (filename, module name) (for dynamically loaded modules), containing these
+        modules.  A copy of the module's dictionary is stored by calling
+        _PyImport_FixupExtensionObject() immediately after the module initialization
+        function succeeds.  A copy can be retrieved from there by calling
+        _PyImport_FindExtensionObject().
 
    Modules which do support multiple initialization set their m_size
    field to a non-negative number (indicating the size of the
@@ -505,7 +505,7 @@
         if (def->m_base.m_copy == NULL)
             return -1;
     }
-    PyDict_SetItem(extensions, filename, (PyObject*)def);
+    PyDict_SetItem(extensions, PyTuple_Pack(2,filename, name), (PyObject*)def);
     return 0;
 }
 
@@ -529,7 +529,7 @@
     PyModuleDef* def;
     if (extensions == NULL)
         return NULL;
-    def = (PyModuleDef*)PyDict_GetItem(extensions, filename);
+    def = (PyModuleDef*)PyDict_GetItem(extensions, PyTuple_Pack(2, filename, name));
     if (def == NULL)
         return NULL;
     if (def->m_size == -1) {