According to https://mail.python.org/archives/list/distutils-sig@python.org/message/OXN53BWJYSMFK535OWUJR5MAXEIBWRBX/, some time since https://www.python.org/dev/peps/pep-0440/#summary-of-differences-from-pkg-resources-parse-version was written, pkg_resource.parse_version started ordering local version numbers the same way that PEP 440 does.

@jaraco Do you have any idea when that might have changed? https://setuptools.readthedocs.io/en/latest/history.html doesn't call it out explicitly anywhere, so I'm wondering if it might have happened inadvertently while converging on a shared supported library.