Comment 37 for bug 1813147

So one issue is we're getting a giant traceback because these tests are using the CastAsCall fixture and we're not registering an expected_exception so we get a big traceback from oslo.messaging:

b'2019-05-02 03:23:44,434 ERROR [oslo_messaging.rpc.server] Exception during message handling'

We could (1) stub that out for the test run or (2) convert the tests to not use the CastAsCall fixture. (2) is probably better long-term but might not be very easy.