repofilecache: define a 'join' method

We are about to turn the 'join' method of the base class Abstract, so we need
on to be defined in the localrepo. The ultimate goal here is to be able to stop
relying for the 'localrepo' class to have a 'join' methods (there is above one
hundred methods on 'localrepo'. This change make te 'repo' file cache have its
own code so that we can prepare this change to the repostory class.


explicite join

mercurial/localrepo.py

@@ -70,6 +70,8 b' class repofilecache(scmutil.filecache):'
     """All filecache usage on repo are done for logic that should be unfiltered
     """
 
+    def join(self, obj, fname):
+        return obj.join(fname)
     def __get__(self, repo, type=None):
         if repo is None:
             return self