Well, it is a breaking change on a minor revision, but Python doesn't use semantic versioning so there's no reason that can't happen. The relevant PEP, https:/

Well, it is a breaking change on a minor revision, but Python doesn't use semantic versioning so there's no reason that can't happen. The relevant PEP, https://www.python.org/dev/peps/pep-0387/ https://www.python.org/dev/peps/pep-0387/, states that breaking changes may be made with two minor versions of warning (or one major version). Minor versions are released on a calendar schedule (again, not semantic versioning), so this policy is 2-3 years of warning in practice.