--- a/mercurial/__init__.py	Mon Jul 08 13:10:34 2019 -0700
+++ b/mercurial/__init__.py	Sun Jul 07 23:04:55 2019 -0700
@@ -29,7 +29,7 @@
         """A sys.meta_path finder that uses a custom module loader."""
         def find_spec(self, fullname, path, target=None):
             # Only handle Mercurial-related modules.
-            if not fullname.startswith(('mercurial.', 'hgext.', 'hgext3rd.')):
+            if not fullname.startswith(('mercurial.', 'hgext.')):
                 return None
             # don't try to parse binary
             if fullname.startswith('mercurial.cext.'):