--- a/mercurial/rewriteutil.py	Mon Mar 29 01:52:06 2021 +0200
+++ b/mercurial/rewriteutil.py	Tue Apr 27 11:02:41 2021 -0700
@@ -34,7 +34,7 @@
     Make sure this function is called after taking the lock.
     """
     if nullrev in revs:
-        msg = _(b"cannot %s null changeset") % action
+        msg = _(b"cannot %s the null revision") % action
         hint = _(b"no changeset checked out")
         raise error.InputError(msg, hint=hint)