We had an extension-related test that would try to simulate two threads
trying to install media files at the same time, to ensure our locks were
working. Sometimes, this would fail, particularly if the computer was
under heavy load.

We now have each thread sleep for a different amount of time before
attemping the lock. The result is that the lock gets hit consistently.

Ran the tests a couple dozen times. Couldn't reproduce the failure. I was

able to hit it more consistently than that before.