"No tests were found" when running test in debugger

When I run a test in the PyCharm debugger, instead of reporting that the test failed, I get, "No tests were found," and at the bottom of the console I see the following:

Ran 7 tests in 1.955s

FAILED (failures=1)

Destroying test database 'default'...

Exception AttributeError: "'NoneType' object has no attribute 'print_exc'" in <bound method Signal._remove_receiver of <django.dispatch.dispatcher.Signal object at 0x100712790>> ignored

Empty test suite.

Process finished with exit code 1

I'm not sure if this has anything to do with this issue, but I also see ths follwing related to psyco:

pydev debugger: warning: psyco not available for speedups (the debugger will still work correctly, but a bit slower)

pydev debugger: starting