Unable to check requirements files containing non-editable mode URLs

[edmorley]

STR:

1. Create a requirements file containing:

requests
https://github.com/jeads/datasource/archive/v0.10.0.tar.gz#egg=datasource==0.10.0

2. Drag onto the text area on https://caniusepython3.com/ and press check

Expected:
Ideally both requirements checked, or failing that at least the check run against the non-URL requirement (requests).

Actual:

Couldn't check ['https://github.com/jeads/datasource/archive/v0.10.0.tar.gz#egg=datasource==0.10.0'].

Adding -e prior to the URL prevents the error. However bare URLs are allowed according to:
https://pip.readthedocs.org/en/stable/reference/pip_install/#requirements-file-format