At my current company we’re in an awkward situation with python 2.7.1 and 2.7.5, I’ve found that a easy solution to circular dependencies caused by the new resolver is installing pip==20.2.4 and an older setuptools (I don’t have this version memorized) before doing anything.
So if it isn't in the standard library, I haven't been using it. Pity, because lxml seems like it would solve some of my issues.