--- a/mercurial/revset.py	Sat Aug 13 04:21:42 2016 +0530
+++ b/mercurial/revset.py	Mon Aug 15 12:26:02 2016 -0400
@@ -2433,6 +2433,9 @@
     elif op == 'list':
         ws, ts = zip(*(_optimize(y, small) for y in x[1:]))
         return sum(ws), (op,) + ts
+    elif op == 'keyvalue':
+        w, t = _optimize(x[2], small)
+        return w, (op, x[1], t)
     elif op == 'func':
         f = getsymbol(x[1])
         wa, ta = _optimize(x[2], small)