narrow: fix crash when restoring backup in legacy repo
Using --addremove when committing in an old repo (before we started
keeping .hg/narrowspec.dirstate) results in a crash. The test
case modified in this patch would crash like this:
abort: $ENOENT$
The issue is that when the dirstateguard is aborted, it tries to
restore the backup of .hg/narrowspec.dirstate. However, since we were
in an old repo, that file did not get created when the dirstateguard
was created. Note that the dirstateguard is not used unless
--addremove is passed.
This patch fixes the bug by making restorewcbackup() not fail if the
backup doesn't exist. I also made clearwcbackup() safe, just in case.
Differential Revision: https://phab.mercurial-scm.org/D5634
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Am0
adding a
$ echo b > b
$ hg ci -Am1
adding b
$ hg tag -r0 default
warning: tag default conflicts with existing branch name
$ hg log
changeset: 2:30a83d1e4a1e
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag default for changeset f7b1eb17ad24
changeset: 1:925d80f479bb
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 0:f7b1eb17ad24
tag: default
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
$ hg update 'tag(default)'
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ hg parents
changeset: 0:f7b1eb17ad24
tag: default
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
$ hg update 'branch(default)'
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg parents
changeset: 2:30a83d1e4a1e
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag default for changeset f7b1eb17ad24
$ cd ..