--- a/mercurial/filelog.py	Wed Mar 10 18:09:21 2021 +0100
+++ b/mercurial/filelog.py	Wed Jan 13 16:14:58 2021 +0100
@@ -33,6 +33,7 @@
         # Used by LFS.
         self._revlog.filename = path
         self._revlog.revlog_kind = b'filelog'
+        self.nullid = self._revlog.nullid
 
     def __len__(self):
         return len(self._revlog)