--- a/mercurial/cmdutil.py	Sun Oct 06 13:17:19 2019 -0400
+++ b/mercurial/cmdutil.py	Sun Oct 06 13:28:56 2019 -0400
@@ -19,6 +19,7 @@
     nullrev,
     short,
 )
+from .pycompat import open
 
 from . import (
     bookmarks,