[PATCH 3 of 5] revsets: use itervalues() where only values are needed

[Martin von Zweigbergk]

# HG changeset patch
# User Martin von Zweigbergk <martinvonz at google.com>
# Date 1466712490 25200
#      Thu Jun 23 13:08:10 2016 -0700
# Node ID 4fc03f313a06f6f1ba9638d2692351de064e8482
# Parent  452eef4be6b5acbde6b0fd988f6aab27a1c144d1
revsets: use itervalues() where only values are needed

I don't think there will be a noticeable speedup, but it removes an
unused variable.

diff -r 452eef4be6b5 -r 4fc03f313a06 mercurial/revset.py
--- a/mercurial/revset.py	Thu Jun 23 13:08:08 2016 -0700
+++ b/mercurial/revset.py	Thu Jun 23 13:08:10 2016 -0700
@@ -1143,7 +1143,7 @@
     getargs(x, 0, 0, _("head takes no arguments"))
     hs = set()
     cl = repo.changelog
-    for b, ls in repo.branchmap().iteritems():
+    for ls in repo.branchmap().itervalues():
         hs.update(cl.rev(h) for h in ls)
     # XXX We should combine with subset first: 'subset & baseset(...)'. This is
     # necessary to ensure we preserve the order in subset.