Thank you for the contribution. Since we are testing in CI only against supported Python versions, these regressions are somewhat inevitable, I guess. Most of the codebase used to work with Python 2.7 but retaining that compatibility cannot be guaranteed even within the same major semver, because we are not going to have tests for it. I am happy to merge this though and I am happy to accept future contributions to help us maintain that compatibility if it breaks again in the future.

It's like tier1 and tier2 python version system. Tier1 are the versions that we have in CI, Tier2 - all the rest. Maybe we should write that in our docs.