--- a/mercurial/templater.py	Thu Jun 22 01:29:07 2017 +0530
+++ b/mercurial/templater.py	Thu Jun 22 03:10:24 2017 +0530
@@ -1303,6 +1303,7 @@
         return stringify(self('', **mapping))
 
     def __call__(self, t, **mapping):
+        mapping = pycompat.byteskwargs(mapping)
         ttype = t in self.map and self.map[t][0] or 'default'
         if ttype not in self.ecache:
             try: