# HG changeset patch
# User FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
# Date 2016-06-12 20:11:56
# Node ID bebe7d1c38c855e97f51dfb8ad808f9c9c483533
# Parent  35861cc1076ecb3d1552d34b6f2311349c150070

dirstate: make restoring from backup avoid ambiguity of file stat

File .hg/dirstate is restored by renaming from backup in failure
inside scopes below. If renaming keeps ctime, mtime and size of a
file, restoring is overlooked, and old contents cached before
restoring isn't invalidated as expected.

  - dirstateguard scope (from '.hg/dirstate.SUFFIX')
  - transaction scope (from '.hg/journal.dirstate')

To avoid ambiguity of file stat at restoring, this patch invokes
vfs.rename() with checkambig=True.

This patch is a part of "Exact Cache Validation Plan":

    https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan

diff --git a/mercurial/dirstate.py b/mercurial/dirstate.py
--- a/mercurial/dirstate.py
+++ b/mercurial/dirstate.py
@@ -1243,7 +1243,8 @@ class dirstate(object):
         self.invalidate()
         filename = self._actualfilename(tr)
         # using self._filename to avoid having "pending" in the backup filename
-        self._opener.rename(prefix + self._filename + suffix, filename)
+        self._opener.rename(prefix + self._filename + suffix, filename,
+                            checkambig=True)
 
     def clearbackup(self, tr, suffix='', prefix=''):
         '''Clear backup file with suffix'''