Message 330269 - Python tracker

Honestly, I'm not convinced that the change is worth it. It looks like a giant complication for a very specific use case, whereas the current _PyMem_SetDefaultAllocator() solution "works". I close the issue.

Moreover, bpo-35266 conflicts with issue, and bpo-35266 looks more important than this issue, since it impacts the future public API and remove redundancy.