``test_asyncio.test_base_events`` leaks references in free-threaded build

[Eclips4]

Bug report

Bug description:

eclips4@nixos ~/p/p/cpython (main)> ./python -m test -R 3:3 test_asyncio.test_base_events
Using random seed: 315532800
0:00:00 load avg: 7.88 Run 1 test sequentially in a single process
0:00:00 load avg: 7.88 [1/1] test_asyncio.test_base_events
beginning 6 repetitions. Showing number of leaks (. for 0 or less, X for 10 or more)
123:456
XX3 333
test_asyncio.test_base_events leaked [3, 3, 3] references, sum=9
test_asyncio.test_base_events failed (reference leak)

== Tests result: FAILURE ==

1 test failed:
 test_asyncio.test_base_events

Total duration: 18.4 sec
Total tests: run=111
Total test files: run=1/1 failed=1
Result: FAILURE

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-124068: Fix reference leak with generators in the free-threaded build #124069

[Eclips4]

Bisected to 8810e28

[picnixz]

cc @Fidget-Spinner @colesbury @markshannon (technically, @me as well since I've been involved :'))

[colesbury]

I'll take a look. I saw something similar when working on #124026 with a reference leak involving generators/coroutines and exceptions frames.