gh-141510: Use frozendict for errno.errorcode by vstinner · Pull Request #144906 · python/cpython

Just to be clear: I'm not saying it's possible on purpose, just that I think it is a useful property even if it wasn't on purpose, and I do think we have to consider that people are using the mutability. That's the case for any existing, exposed dict: it may not make sense to mutate it, but maybe we just don't see the cases where it does make sense. We have to consider whether the change is worth the potential breakage, so I think we need a good, real-world reason to replace the dict with a frozendict, not just a theoretical, common-sense one.