clfilter: do not use tags cache if there are filtered changesets

If there are filtered changesets the cache is not valid. We'll have to cache
tags for filtered state too, but for now recomputing the tags is enough.

mercurial/localrepo.py

@@ -516,7 +516,11 b' class localrepository(object):'
     def tags(self):
         '''return a mapping of tag to node'''
         t = {}
-        for k, v in self._tagscache.tags.iteritems():
+        if self.changelog.filteredrevs:
+            tags, tt = self._findtags()
+        else:
+            tags = self._tagscache.tags
+        for k, v in tags.iteritems():
             try:
                 # ignore tags to unknown nodes
                 self.changelog.rev(v)