--- a/mercurial/templater.py	Fri Dec 29 05:29:57 2017 +0530
+++ b/mercurial/templater.py	Fri Dec 29 05:31:27 2017 +0530
@@ -397,7 +397,7 @@
         # pair instead of **props
         props = context._resources.copy()
         props.update(mapping)
-        return v(**props)
+        return v(**pycompat.strkwargs(props))
     return v
 
 def buildtemplate(exp, context):