subrepo: do not traceback on .hgsubstate parsing errors
Note that aborting in subrepo.state() prevents "repairing" commands like revert
to be issued. The user will have to edit the .hgsubstate manually (but he
probably had already otherwise this would not be failing). The same behaviour
already happens with invalid .hgsub entries.
$ 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