diff -r 0d612db7047c -r c59eb1560c44 mercurial/revlogutils/deltas.py
--- a/mercurial/revlogutils/deltas.py	Sun Oct 06 16:39:13 2019 -0400
+++ b/mercurial/revlogutils/deltas.py	Sun Oct 06 16:55:18 2019 -0400
@@ -15,6 +15,7 @@
 # import stuff from node for others to import from revlog
 from ..node import nullrev
 from ..i18n import _
+from ..pycompat import getattr
 
 from .constants import (
     REVIDX_ISCENSORED,