It's a interesting thing. I wonder what it's telling us.

Perhaps it has found a bug for which there is no other test coverage yet existing. For example, perhaps the message timestamp values are coming back as integers on this platform. Or perhaps one the calls to self.bus1.recv is choking on one of the arguments that the testcase is passing it.

Disclaimer: I just had to Google what pypy is, so please disregard if you think this comment could well be nonsense.