Revert "Merge pull request #3578 from davidhewitt/typed-helpers"

[davidhewitt]

This reverts #3578, setting the return type of py.None(), py.NotImplemented(), and py.Ellipsis() back to PyObject instead of GIL Ref to their typed singletons.

I still believe that returning better typed values would be a good thing, but now with the migration to the GIL Refs API also landing in 0.21 I think that the extra churn caused by this change is not helpful right at this minute. In particular because this patch changed py.None() to return &PyNone, which is a GIL Ref API, introducing that change right now feels in contradiction with the general theme of the 0.21 release.

I propose to revert this change for now and land it in a few releases time as Borrowed<PyNone> etc as the future return types, when the rest of the dust has settled a bit.

[davidhewitt]

cc @messense / @adamreichold as you were original reviewers here. As this code never made it into a release, I'm going to just proceed to merge this revert immediately to make the job cleaner for @snuderl in #3793

[codspeed-hq]

CodSpeed Performance Report

Merging #3794 will degrade performances by 13.51%

_{Comparing davidhewitt:revert-python-none (76d1b34) with main (d8c5e79)}

Summary

⚡ 1 improvements
❌ 2 regressions
✅ 76 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	davidhewitt:revert-python-none	Change
⚡	list_via_downcast	185 ns	157.2 ns	+17.67%
❌	not_a_list_via_downcast	215 ns	242.8 ns	-11.44%
❌	f64_from_pyobject	711.1 ns	822.2 ns	-13.51%