PyPI sdist installs into "src"

If I fetch the sdist from PyPI https://files.pythonhosted.org/packages/53/17/53bd32842cac710fa1a7956044eec745251fa9f81e99bddfa99b9e6e1ac3/openapi-cli-tool-0.3.0.tar.gz , and run `python3 setup.py install`, it installs into `/usr/lib/pythonX.Y/site-packages/src/...`