[PATCH 1 of 3] revset: make optimize() reject unknown operators

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1470549702 -32400
#      Sun Aug 07 15:01:42 2016 +0900
# Node ID 5cb90003deb87ae58f620657ec891df26e04c72a
# Parent  d130a38ef41f3c9e2d2f26df3535d89a93f87301
revset: make optimize() reject unknown operators

This should have caught the bug of 'keyvalue' operator fixed at 5004ef47f437.
The catch-all pattern is useless since optimize() should be aware of all known
operators.

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -2463,7 +2463,7 @@ def _optimize(x, small):
         else:
             w = 1
         return w + wa, (op, x[1], ta)
-    return 1, x
+    raise ValueError('invalid operator %r' % op)
 
 def optimize(tree):
     _weight, newtree = _optimize(tree, small=True)