# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@fb.com>
# Date 2014-09-17 18:00:03
# Node ID 6f434ef5422269dc95c315ccb899ef4d5b3c38b8
# Parent  a428db9ab61ddd870983eda1e0bf4d328c7b32c0

revset: use `subset &` in bare `p2()`

This takes advantage of the `fullreposet` smartness with a nice
speedup. It's a similar speedup to `p1()` when a merge is in progress
(the non merge case is already lightning fast anyway.)

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -1217,7 +1217,9 @@ def p2(repo, subset, x):
         ps = repo[x].parents()
         try:
             p = ps[1].rev()
-            return subset.filter(lambda r: r == p)
+            if p >= 0:
+                return subset & baseset([p])
+            return baseset([])
         except IndexError:
             return baseset([])