[PATCH 1 of 2] py3: pass in system string to vars(branchmap).__contains__()

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1539421086 -7200
#      Sat Oct 13 10:58:06 2018 +0200
# Node ID 7e85eb3b267f431106e6f523786712ca6a9ec4df
# Parent  0b46e1aa77609c48e77f73ef987807f4a123d6a5
py3: pass in system string to vars(branchmap).__contains__()

diff --git a/mercurial/branchmap.py b/mercurial/branchmap.py
--- a/mercurial/branchmap.py
+++ b/mercurial/branchmap.py
@@ -480,7 +480,7 @@ class revbranchcache(object):
         #   self.branchinfo = self._branchinfo
         #
         # Since we now have data in the cache, we need to drop this bypassing.
-        if 'branchinfo' in vars(self):
+        if r'branchinfo' in vars(self):
             del self.branchinfo
 
     def _setcachedata(self, rev, node, branchidx):