--- a/mercurial/util.py	Sun Oct 06 16:55:18 2019 -0400
+++ b/mercurial/util.py	Sun Oct 06 16:58:55 2019 -0400
@@ -36,6 +36,7 @@
 
 from .thirdparty import attr
 from .pycompat import (
+    delattr,
     getattr,
     open,
     setattr,