--- a/hgext/git/index.py	Fri Apr 30 02:11:58 2021 +0200
+++ b/hgext/git/index.py	Mon May 03 18:55:19 2021 +0200
@@ -278,7 +278,7 @@
     for pos, commit in enumerate(walker):
         if prog is not None:
             prog.update(pos)
-        p1 = p2 = sha1nodeconstants.nullhex
+        p1 = p2 = gitutil.nullgit
         if len(commit.parents) > 2:
             raise error.ProgrammingError(
                 (