auto-upgrade: skip the operation if the repository cannot be locked This seems like a fine default behavior for now. If some users wants something more aggressive we can make the behavior configurable in the future. Differential Revision: https://phab.mercurial-scm.org/D12619

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