I'm working on a PR that finally changes the DeprecationWarnings that Serhiy introduced to TypeErrors; I think that should be acceptable, four Python versions and some years later. With that PR:

- int will always return something of exact type `int` (or raise)
- operator.index will always return something of exact type `int` (or raise)
- PyNumber_Index will always use `__index__` for int subclasses, so this should fix the issue that Barry originally reported (mismatch between `obj.__index__()` and `operator.index(obj)`).