clfilter: make localpeer use a repo with "unserved" filter

This changeset installs a broad filter on most repos used for
serving. This removes the need to use the `visiblehead`/`visiblebranchmap`
functions, and ensures that changesets we should not serve are in
fact never served.

We do not use filtering on hgweb yet, as there is still a number
of issues to solve there.

mercurial/localrepo.py

@@ -66,7 +66,7 b' class localpeer(peer.peerrepository):'
 
     def __init__(self, repo, caps=MODERNCAPS):
         peer.peerrepository.__init__(self)
-        self._repo = repo
+        self._repo = repo.filtered('unserved')
         self.ui = repo.ui
         self._caps = repo._restrictcapabilities(caps)
         self.requirements = repo.requirements

tests/test-wireproto.py

@@ -25,6 +25,9 b' class serverrepo(object):'
     def greet(self, name):
         return "Hello, " + name
 
+    def filtered(self, name):
+        return self
+
 def mangle(s):
     return ''.join(chr(ord(c) + 1) for c in s)
 def unmangle(s):