We were having trouble with wheel creation, which apparently has to do with an older version of setuptools adding Requires-Dist: windows-curses; for all systems, which will break on linux.
The TODO from @gtback's analysis (last comment of PR 45).
"I'd recommend just using a newer version of the CircleCI Python Docker image in .circleci/config.yml, and verify it has a new-enough version of setuptools."