https://travis-ci.org/wikimedia/pywikibot-core/jobs/188038123#L3853:
=================================== FAILURES =================================== ______________________ HttpServerProblemTestCase.test_502 ______________________ self = <tests.tests_tests.HttpServerProblemTestCase testMethod=test_502> def test_502(self): """Test a HTTP 502 response using http://httpbin.org/status/502.""" > self.fail('The test framework should skip this test.') E AssertionError: The test framework should skip this test.
It has appeared after 431e72083ac18a (T153560), but I'm not sure if it's the actual cause or not.