I just opened a pull request that makes a minor change to how you run the yt unit tests in some cases:

See the pull request description for more details.

I'm raising this on the mailing list because it will impact how you run the unit tests if you specify a path to a test file. I would very much appreciate hearing from anyone that has concerns about this. Just raising it here out of an abundance of caution, I expect everyone to be pretty happy with this change as it's a common source of user error when running tests locally.

-Nathan