Allow "file://localhost/" in addition to "file:///" (issue728)

file://localhost/ URLs are generated by Mac OS X API calls like
[NSURL fileURLWithPath:].

Imported patch from Paul Bx.

mercurial/hg.py

@@ -119,6 +119,8 b' def clone(ui, source, dest=None, pull=Fa'
         ui.status(_("destination directory: %s\n") % dest)
 
     def localpath(path):
+        if path.startswith('file://localhost/'):
+            return path[16:]
         if path.startswith('file://'):
             return path[7:]
         if path.startswith('file:'):