Current state
Currently test_swift.WikimediaSwiftTestCase.mock_get_object() isn't triggered while test_swift.py is running.
I have checked that it is even on the Dockerized Python2 version of thumbor-plugins. So, it looks like the migration to Python3 didn't cause it.
Expected result
test_swift.WikimediaSwiftTestCase.mock_get_object() is triggered during running test_swift.py.