auto-upgrade: add a test case where the repository is already locked
This show the current behavior when the repository to auto-upgrade is already
locked.
The current behavior is to abort, which is probably not great. Now that we have
a proper test, we can think about the behavior we wants in a later tests.
Differential Revision: https://phab.mercurial-scm.org/D12618
Set up
$ hg init repo
$ cd repo
Try to import an empty patch
$ hg import --no-commit - <<EOF
> EOF
applying patch from stdin
abort: stdin: no diffs found
[10]
No dirstate backups are left behind
$ ls .hg/dirstate* | sort
.hg/dirstate