# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 1552262978 -3600
# Node ID 2930b31383af4e24a5afeacd67c5a213db46de4f
# Parent  ade02721d3fa29aa874b7de7e913bd811631ff25
hgtagsfnodescache: handle nullid lookup

The null revision is empty, so it `.hgtags` content is `nullid` in regards with
the `hgtagsfnodescache`. Dealing with `nullid` will help with the next
changeset. Before this change, feeding `nullid` to `hgtagsfnodescache.getfnode` would
return a wrong result (fnode for tip).

diff -r ade02721d3fa -r 2930b31383af mercurial/tags.py
--- a/mercurial/tags.py	Fri Apr 26 17:39:07 2019 +0200
+++ b/mercurial/tags.py	Mon Mar 11 01:09:38 2019 +0100
@@ -691,6 +691,9 @@
         If an .hgtags does not exist at the specified revision, nullid is
         returned.
         """
+        if node == nullid:
+            return nullid
+
         ctx = self._repo[node]
         rev = ctx.rev()