localrepo: clear _filecache earlier to really force reloading (issue3462)

ce0ad184f489 attempted to force the filecaches in localrepo to reload
everything after a rollback. But simply clearing _filecache isn't enough,
invalidate() needs to be called before/after. localrepo._rollback calls
invalidate() already, so we clear the map right afterwards which ensures
everything will be reread.

mercurial/localrepo.py

@@ -833,6 +833,9 b' class localrepository(repo.repository):'
                         self.sjoin('phaseroots'))
         self.invalidate()
 
+        # Discard all cache entries to force reloading everything.
+        self._filecache.clear()
+
         parentgone = (parents[0] not in self.changelog.nodemap or
                       parents[1] not in self.changelog.nodemap)
         if parentgone:
@@ -1316,9 +1319,6 b' class localrepository(repo.repository):'
         # tag cache retrieval" case to work.
         self.invalidatecaches()
 
-        # Discard all cache entries to force reloading everything.
-        self._filecache.clear()
-
     def walk(self, match, node=None):
         '''
         walk recursively through the directory tree or a given