[PATCH 5 of 5] cleanup: replace False identity testing with an explicit token object

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at ens-lyon.org>
# Date 1462469571 -7200
#      Thu May 05 19:32:51 2016 +0200
# Node ID b62cf5924c3b5684cb0693fe4186dc607dcc5b50
# Parent  685102426f222a6746960a905e2392cc2c4607da
# EXP-Topic cleanup
cleanup: replace False identity testing with an explicit token object

The recommended way to check default value (when None is not as option) is a
token object. Identity testing to integer is less explicit and not guaranteed to
work in all implementations.

diff -r 685102426f22 -r b62cf5924c3b mercurial/dirstate.py
--- a/mercurial/dirstate.py	Wed May 11 09:31:47 2016 +0200
+++ b/mercurial/dirstate.py	Thu May 05 19:32:51 2016 +0200
@@ -74,6 +74,8 @@ def _trypending(root, vfs, filename):
                 raise
     return (vfs(filename), False)
 
+_token = object()
+
 class dirstate(object):
 
     def __init__(self, opener, ui, root, validate):
@@ -688,12 +690,12 @@ class dirstate(object):
         self._pl = (parent, nullid)
         self._dirty = True
 
-    def write(self, tr=False):
+    def write(self, tr=_token):
         if not self._dirty:
             return
 
         filename = self._filename
-        if tr is False: # not explicitly specified
+        if tr is _token: # not explicitly specified
             self._ui.deprecwarn('use dirstate.write with '
                                'repo.currenttransaction()',
                                '3.9')