So today I did found out that with the release of pip 10.x.x the req package changed its directory and can now be found under pip._internal.r
What I figured out the right way to do is adding the dependencies in the setup.py like:
REQUIRED_PACKAGES = [
'boto3==1.7.33'
]
if __name__ == '__main__':
setup(
...
install_requires=REQUIRED_PACKAGES,
...
)
and just have a . in your requirements.txt. It will then automatically install all packages from the setup.py if you install from the file.