A minimal repro repo for the problem described here
To see the issue, run:
./pants setup-py python/my-library::
And then from a python3 virtualenv try to install the generated package.
(python3) $ pip install dist/Mylibrary-0.1.0.tar.gz Processing ./dist/Mylibrary-0.1.0.tar.gz Complete output from command python setup.py egg_info: error in Mylibrary setup command: 'install_requires' must be a string or list of strings containing valid project/version requirement specifiers; 'int' object is not iterable