ui: deprecated `ui.expandpath`

This function return a single path, something incompatible with the coming
change to `[paths]` definition to allow multiple associated urls.

Now that all user got migrated, we deprecate the function.

Differential Revision: https://phab.mercurial-scm.org/D10432

mercurial/ui.py

@@ -1030,6 +1030,8 b' class ui(object):'
 
     def expandpath(self, loc, default=None):
         """Return repository location relative to cwd or from [paths]"""
+        msg = b'ui.expandpath is deprecated, use `get_*` functions from urlutil'
+        self.deprecwarn(msg, b'6.0')
         try:
             p = self.getpath(loc)
             if p: