So this was a random one-off (hardly even intermittent) failed test that passed on the retry.  Ah, threads.  Is there an easy way to find all other failures in test_threaded_import in the past, for this and for all buildbots?  Do we have information about load during tests?  Is there an easy way to run the test suite under load on a build bot?

With a large enough sample size we can make more sense of this.  For instance, do failures predate the addition of per-module import locks or the importlib migration in 3.3?  Are failures limited to particular platforms?  Is the problem load related?

BTW, test_threaded_import had another (different) failure a week ago on FreeBSD: issue15599.