--- a/mercurial/mdiff.py	Sun Oct 06 14:51:45 2019 -0400
+++ b/mercurial/mdiff.py	Sun Oct 06 14:58:42 2019 -0400
@@ -12,6 +12,7 @@
 import zlib
 
 from .i18n import _
+from .pycompat import setattr
 from . import (
     encoding,
     error,