python's dev-requirements.txt is incompatible with pip 20.3.3

Trying to build v4.4 from sources as described in https://github.com/mongodb/mongo/blob/v4.4/docs/building.md

When I run following command with latest pip version (20.3.3) it never finishes:

pip install -r etc/pip/dev-requirements.txt

With previous pip version (20.2.2) the same command finishes in few seconds.

I believe this behavior is caused by this issue in the new pip's dependency resolver implementation: https://github.com/pypa/pip/issues/9215