localrepo: use cg?unpacker.apply() instead of changegroup.addchangegroup()

This is in localpeer, so it lives. Had it been in localrepo instead, I
would have tried to exterminate it.

mercurial/localrepo.py

@@ -159,7 +159,7 b' class localpeer(peer.peerrepository):'
         return self._repo.lock()
 
     def addchangegroup(self, cg, source, url):
-        return changegroup.addchangegroup(self._repo, cg, source, url)
+        return cg.apply(self._repo, source, url)
 
     def pushkey(self, namespace, key, old, new):
         return self._repo.pushkey(namespace, key, old, new)