Clone this repo, then execute this workflow:

python3 -m venv venv
source venv/bin/activate
pip install pip==20.1.1
pip install pip-tools==5.2.1
pip-compile requirements.in > requirements.txt
pip install -e .

The last command will exit with this error:

    error in pkg setup command: 'install_requires' must be a string or list of
    strings containing valid project/version requirement specifiers; Invalid
    requirement, parse error at "'+https:/'"
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check
the logs for full command output.

The same workflow with pip 20.0.2 works without errors.

The created requirements.txt includes

git+https://github.com/gtaylor/python-colormath.git@6cb12bf#egg=colormath@https://github.com/gtaylor/python-colormath/tarball/6cb12bf  # via -r requirements.in

Compared to the requirements.in, the name colormath at the beginning was removed.

If I manually modify this line in requirements.txt to include the name

colormath @ git+https://github.com/gtaylor/python-colormath.git@6cb12bf#egg=colormath@https://github.com/gtaylor/python-colormath/tarball/6cb12bf  # via -r requirements.in

then pip install -e . runs fine in pip 20.1.1 (and this still works with pip 20.0.2).

Does that mean that pip-compile should include the package name when generating a VCS-url requirement? Need to check PEP 440 and PEP 508