Use the mercurial i18n infrastructure in the purge extension

contrib/purge/purge.py

@@ -18,11 +18,9 b''
 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 
 from mercurial import hg, util
+from mercurial.i18n import _
 import os
 
-def _(s):
-    return s
-
 class Purge(object):
     def __init__(self, act=True, abort_on_err=False, eol='\n'):
         self._repo = None