PyCharm 5 regression: Ctrl-Shift-F10 to run unittest class or method

I used to be able to have my cursor on a test method and hit Ctrl-Shift-F10 to run the unit test. This no longer works.

I checked the test class hierarchy, and it seems PyCharm is not finding that testtools.TestCase is derived from unittest.TestCase. I suspect that therefore it thinks my test method is not a unittest.