diff -r 594e84a2e574 -r 300f8564220f mercurial/localrepo.py
--- a/mercurial/localrepo.py	Tue Nov 20 10:46:20 2018 +0000
+++ b/mercurial/localrepo.py	Tue Nov 20 10:38:15 2018 +0000
@@ -1417,10 +1417,11 @@
             tags, tt = self._findtags()
         else:
             tags = self._tagscache.tags
+        rev = self.changelog.rev
         for k, v in tags.iteritems():
             try:
                 # ignore tags to unknown nodes
-                self.changelog.rev(v)
+                rev(v)
                 t[k] = v
             except (error.LookupError, ValueError):
                 pass