templater: evaluate "query" argument passed to revset() stable

templater: evaluate "query" argument passed to revset()

revset() had the same issue as 9452112c8eb0. It crashed by passing non-string
expression.

--- a/mercurial/templater.py	Sat Jun 20 19:59:26 2015 -0400
+++ b/mercurial/templater.py	Sat Jun 20 23:13:34 2015 +0900
@@ -417,7 +417,7 @@
         # i18n: "revset" is a keyword
         raise error.ParseError(_("revset expects one or more arguments"))
 
-    raw = args[0][1]
+    raw = stringify(args[0][0](context, mapping, args[0][1]))
     ctx = mapping['ctx']
     repo = ctx.repo()
 

--- a/tests/test-command-template.t	Sat Jun 20 19:59:26 2015 -0400
+++ b/tests/test-command-template.t	Sat Jun 20 23:13:34 2015 +0900
@@ -2527,6 +2527,9 @@
   Rev: 0
   Ancestor: 0
   
+  $ hg log --template '{revset("TIP"|lower)}\n' -l1
+  2
+
 Test current bookmark templating
 
   $ hg book foo