dirstate: add filecache support

mercurial/dirstate.py

@@ -52,6 +52,7 b' class dirstate(object):'
         self._dirtypl = False
         self._lastnormaltime = 0
         self._ui = ui
+        self._filecache = {}
 
     @propertycache
     def _map(self):

mercurial/localrepo.py

@@ -901,10 +901,13 b' class localrepository(repo.repository):'
         rereads the dirstate. Use dirstate.invalidate() if you want to
         explicitly read the dirstate again (i.e. restoring it to a previous
         known good state).'''
-        try:
+        if 'dirstate' in self.__dict__:
+            for k in self.dirstate._filecache:
+                try:
+                    delattr(self.dirstate, k)
+                except AttributeError:
+                    pass
             delattr(self, 'dirstate')
-        except AttributeError:
-            pass
 
     def invalidate(self):
         for k in self._filecache: