Coverage remained the same at 99.812% when pulling 70af1190255242ed675ce1ea7168a05aaeb66ad8 on feature/expand_test_runner_versions into 9cfc4cba0d223e00732f7ebd40b9bc4d989a2ef5 on master.
I am not sure why coveralls is reporting the coverage change of the 2.7 run as negative 0, but rather than fix it, I plan to wait until the problem goes away with deprecation of 2.7 support.
Include python 3.9, and also pypy3, as the README says that it's supported, but never explicitly tested against.