__file__ == None cases

import-and-importlib-notes.md

@@ -39,6 +39,8 @@ importlib.machinery.ModuleSpec:  # Python 3.4+
     name            # __name__
     loader          # __loader__
     origin          # __file__
+                    # None has been seen in the wild (#1042),
+                    # it may indicate a namespace package.
     submodule_search_locations
                     # __path__
                     # None indicates a non-package.