diff -r bbcbb82e3589 -r 66f2cc210a29 mercurial/extensions.py
--- a/mercurial/extensions.py	Sun Oct 06 14:51:45 2019 -0400
+++ b/mercurial/extensions.py	Sun Oct 06 14:58:42 2019 -0400
@@ -18,7 +18,10 @@
     _,
     gettext,
 )
-from .pycompat import open
+from .pycompat import (
+    open,
+    setattr,
+)
 
 from . import (
     cmdutil,