Fix several issues relating to access to source code inside zipfiles. Initial work by Alexander Belopolsky. See Misc/NEWS in this checkin for details.

Lib/runpy.py

@@ -65,13 +65,14 @@ def _run_module_code(code, init_globals=None,
 
 # This helper is needed due to a missing component in the PEP 302
 # loader protocol (specifically, "get_filename" is non-standard)
+# Since we can't introduce new features in maintenance releases,
+# support was added to zipimporter under the name '_get_filename'
 def _get_filename(loader, mod_name):
-    try:
-        get_filename = loader.get_filename
-    except AttributeError:
-        return None
-    else:
-        return get_filename(mod_name)
+    for attr in ("get_filename", "_get_filename"):
+        meth = getattr(loader, attr, None)
+        if meth is not None:
+            return meth(mod_name)
+    return None
 
 # Helper to get the loader, code and filename for a module
 def _get_module_details(mod_name):