pushkey: add an ``encode`` function

pushkey: add an ``encode`` function

This function is just a shorthand for ``encoding.fromlocal``. It will help
hiding the encoding business from other code exchanging pushkey data over the
wire.

--- a/mercurial/pushkey.py	Tue May 27 16:32:50 2014 -0700
+++ b/mercurial/pushkey.py	Thu May 29 15:22:58 2014 -0700
@@ -37,12 +37,13 @@
     lk = _get(namespace)[1]
     return lk(repo)
 
+encode = encoding.fromlocal
+
 decode = encoding.tolocal
 
 def encodekeys(keys):
     """encode the content of a pushkey namespace for exchange over the wire"""
-    enc = encoding.fromlocal
-    return '\n'.join(['%s\t%s' % (enc(k), enc(v)) for k, v in keys])
+    return '\n'.join(['%s\t%s' % (encode(k), encode(v)) for k, v in keys])
 
 def decodekeys(data):
     """decode the content of a pushkey namespace from exchange over the wire"""