--- a/mercurial/revlog.py	Wed Mar 10 18:09:21 2021 +0100
+++ b/mercurial/revlog.py	Wed Jan 13 16:14:58 2021 +0100
@@ -28,6 +28,7 @@
     nullhex,
     nullid,
     nullrev,
+    sha1nodeconstants,
     short,
     wdirfilenodeids,
     wdirhex,
@@ -651,6 +652,10 @@
             raise error.RevlogError(
                 _(b'unknown version (%d) in revlog %s') % (fmt, self.indexfile)
             )
+
+        self.nodeconstants = sha1nodeconstants
+        self.nullid = self.nodeconstants.nullid
+
         # sparse-revlog can't be on without general-delta (issue6056)
         if not self._generaldelta:
             self._sparserevlog = False