pycompat: remove urlunquote alias

pycompat: remove urlunquote alias

It is duplicated by urlreq.unquote and is unused. Kill it.

We retain the imports because it is re-exported via util.urlparse,
which is used elsewhere.

Since we no longer access attributes of urlparse at module load time,
this change /should/ result in that module reverting to a lazy module.

--- a/mercurial/pycompat.py	Tue Mar 21 22:23:11 2017 -0700
+++ b/mercurial/pycompat.py	Tue Mar 21 22:28:16 2017 -0700
@@ -23,7 +23,6 @@
     import Queue as _queue
     import SocketServer as socketserver
     import urlparse
-    urlunquote = urlparse.unquote
     import xmlrpclib
 else:
     import http.client as httplib
@@ -31,7 +30,6 @@
     import queue as _queue
     import socketserver
     import urllib.parse as urlparse
-    urlunquote = urlparse.unquote_to_bytes
     import xmlrpc.client as xmlrpclib
 
 if ispy3: