--- a/mercurial/hgweb/webutil.py	Tue Dec 03 17:17:57 2019 -0800
+++ b/mercurial/hgweb/webutil.py	Thu Dec 05 11:15:19 2019 -0500
@@ -873,7 +873,7 @@
         raise error.ParseError(_(b'not displayable without template'))
 
     def show(self, context, mapping):
-        return self.join(context, b'')
+        return self.join(context, mapping, b'')
 
     def tobool(self, context, mapping):
         return bool(self._vars)