diff -r c2e284cee333 -r eef9a2d67051 mercurial/patch.py
--- a/mercurial/patch.py	Sun Oct 06 13:17:19 2019 -0400
+++ b/mercurial/patch.py	Sun Oct 06 13:28:56 2019 -0400
@@ -24,6 +24,7 @@
     hex,
     short,
 )
+from .pycompat import open
 from . import (
     copies,
     diffhelper,