peer: store the path object used to build a peer from a repo

This is the simplest case, we so starts with it.

mercurial/hg.py

@@ -274,7 +274,7 b' def peer(uiorrepo, opts, path, create=Fa'
             intents=intents,
             createopts=createopts,
         )
-        peer = repo.peer()
+        peer = repo.peer(path=peer_path)
     return peer