util: teach url object about __bytes__

util: teach url object about __bytes__

__str__ tries to do something reasonable, but someone else more
familiar with encoding bugs should check my work.

--- a/mercurial/util.py	Sun Mar 12 03:31:54 2017 -0400
+++ b/mercurial/util.py	Sun Mar 12 03:33:22 2017 -0400
@@ -2651,6 +2651,11 @@
         >>> print url(r'file:///D:\data\hg')
         file:///D:\data\hg
         """
+        if pycompat.ispy3:
+            return encoding.fromlocal(self.__bytes__()).decode('utf-8')
+        return self.__bytes__()
+
+    def __bytes__(self):
         if self._localpath:
             s = self.path
             if self.scheme == 'bundle':