The next step I'd probably try to do is take Pants out of the equation and run directly via Pex. I personally use

pipx install pex

, then it would be something like

pex3 lock create --style=universal --resolver-version=pip-2020-resolver --interpreter-constraint='CPython==3.7.*' --repo=$foo -o debug.lock my-requirement

Not sure on the

--repo

part, depends on how you're using

[python-repos]

whether you use

--repo

vs

--index

-f PATH/URL, --find-links PATH/URL, --repo PATH/URL
                        Additional repository path (directory or URL) to look for requirements.
  -i URL, --index URL, --index-url URL
                        Additional cheeseshop indices to use to satisfy requirements.