Ticket #15114: sys-modules-none.diff

django/utils/module_loading.py

@@ -7 +7 @@
     """See if 'module' is in 'package'."""
     name = ".".join([package.__name__, module_name])
     if name in sys.modules:
-        return True
+        # None indicates a cached miss; see mark_miss() in Python/import.c.
+        return sys.modules[name] is not None
     for finder in sys.meta_path:
         if finder.find_module(name):
             return True

tests/regressiontests/utils/module_loading.py

@@ -25 +25 @@
         self.assertFalse(module_has_submodule(test_module, 'no_such_module'))
         self.assertRaises(ImportError, import_module, 'regressiontests.utils.test_module.no_such_module')
 
+        # Don't be confused by caching of import misses
+        import types  # causes attempted import of regressiontests.utils.types
+        self.assertFalse(module_has_submodule(sys.modules['regressiontests.utils'], 'types'))
+
 class EggLoader(unittest.TestCase):
     def setUp(self):
         self.old_path = sys.path[:]