...and will be removed in the future: https://travis-ci.org/wikimedia/pywikibot/jobs/639814475
This happens because AppVeyor and zh:wikisource Travis environments set PYSETUP_TEST_EXTRAS=1, which sets USE_PYTEST=0, therefore setup.py test is used instead of setup.py pytest: https://phabricator.wikimedia.org/diffusion/PWBC/browse/master/.travis.yml$32