my_package/  # tracks master branch of repository
    setup.py
    my_package/
        __init__.py
        # other stuff

my_package_dev/  # tracks develop branch of repository
    setup.py
    my_package/
        __init__.py
        # other stuff for dev branch

from setuptools import setup
setup(
      name='my_package',  # or 'my_package_dev' for the dev version
      # metadata stuff...
     )