diff -r 4d075bf28702 -r 28dc0030228a mercurial/subrepo.py
--- a/mercurial/subrepo.py	Thu May 26 01:57:34 2016 +0900
+++ b/mercurial/subrepo.py	Thu May 26 01:57:34 2016 +0900
@@ -585,7 +585,7 @@
         return 1
 
     def revert(self, substate, *pats, **opts):
-        self.ui.warn('%s: reverting %s subrepos is unsupported\n' \
+        self.ui.warn(_('%s: reverting %s subrepos is unsupported\n') \
             % (substate[0], substate[2]))
         return []