require python source units to have a setup.py file (fixes #766)
require python source units to have a setup.py file (fixes #766)

techdragon/srclib-python,techdragon/srclib-python,alexsaveliev/srclib-python,alexsaveliev/srclib-python,alexsaveliev/srclib-python,techdragon/srclib-python,sourcegraph/srclib-python