There is an issue where:
1. Lock for asdf.git acquires, which creates asdf.lock
2. asdf.git is cloned into tmp_asdf.git
3. Buildbot crashes, because timeouts
4. neither asdf.lock or tmp_asdf.git/config.lock gets cleaned out on the next unlock.

This aims to fix this issue by aggressively unlocking everything it can find that
vaguely resembles a lock.

BUG=339171

Review URL: https://codereview.chromium.org/187283005

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@255138 0039d316-1c4b-4281-b951-d872f2087c98