--- a/mercurial/pycompat.py	Sun Oct 06 14:51:45 2019 -0400
+++ b/mercurial/pycompat.py	Sun Oct 06 14:58:42 2019 -0400
@@ -355,6 +355,7 @@
     strurl = identity
     bytesurl = identity
     open = open
+    setattr = setattr
 
     # this can't be parsed on Python 3
     exec(b'def raisewithtb(exc, tb):\n' b'    raise exc, None, tb\n')