Message 160972 - Python tracker

sys.modules is tricky thanks to built-in modules not liking to be re-imported (and why import_state in importlib.test didn't reset it).

If only one test fails because of my assumption, then I guess blanking them out really isn't as important as I thought. And if you have to blank everything out for a test, then you are just careful to blank everything out, no matter how verbose it gets.