> In older versions of pip, it is possible for pip to install a package which does not satisfy the declared requirements of another installed package. For example, in pip 20.0, pip install "six<1.12" "virtualenv==20.0.2" does the wrong thing, “successfully” installing six==1.11, even though virtualenv==20.0.2 requires six>=1.12.0,<2 (defined here). The new resolver, instead, outright rejects installing anything if it gets that input.

Shouldn't there be a --force flag of some kind? I know there's another flag, but the name "legacy-resolver" makes it sound like it won't be around forever.

The situation isn't so much asking PIP to revert to an old resolver, so much as it is telling PIP that I know what I'm doing and it should get out of the way.