Since python/cpython#1775 was merged, the coverage build in Travis actually passes all tests. Should we remove the allow_failures key to make sure that it continues to do so? That would mean an extra ~15 minutes between commit and approval from Travis, but as it's already ~20 minutes, I don't think it's that big of a deal. In my experience, I'm not going to sit around waiting for 20 minutes anyway; I'll have moved on to something else long before then and probably won't check back until long after the build has finished.