test_asyncio leaks references after commit 9d2e1ea3862e5950d48b45ac57995a206e33f38b

[pablogsal]

Bug report

Bug description:

Executing

./python -m test test_asyncio.test_subprocess test_asyncio.test_waitfor -R 3:

leaks references on main. Bisecting points to

9d2e1ea3862e5950d48b45ac57995a206e33f38b is the first bad commit
commit 9d2e1ea3862e5950d48b45ac57995a206e33f38b
Author: Kumar Aditya <kumaraditya@python.org>
Date:   Sun Jun 23 18:38:50 2024 +0530

    GH-120804: Remove `PidfdChildWatcher`, `ThreadedChildWatcher` and `AbstractChildWatcher` from asyncio APIs (#120893)

 Lib/asyncio/unix_events.py                | 199 ++++--------------------------
 Lib/test/test_asyncio/test_events.py      |  26 +---
 Lib/test/test_asyncio/test_subprocess.py  |  30 ++---
 Lib/test/test_asyncio/test_unix_events.py |  26 ----
 Lib/test/test_asyncio/utils.py            |  17 ---
 5 files changed, 39 insertions(+), 259 deletions(-)
bisect found first bad commit

Unclear why the buildbots don't catch this but I am catching it everytime I check test_asyncio for refleaks.

CC: @kumaraditya303

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-129158: Ensure we restore unix_events.can_use_pidfd after SubprocessThreadedWatcherTests finishes #129160
• gh-129158: fix CI lint post-merge gh-129160 #129180
• gh-129158: Fix unwanted trailing whitespace in test_asyncio.test_subprocess #129181

[kumaraditya303]

The merged PR broke lint CI on main branch, check https://github.com/python/cpython/actions/runs/12908528443/job/35994236140 https://github.com/python/cpython/actions/runs/12908575929/job/35994388390