[tests] asyncio: test_staggered_race_with_eager_tasks() fails randomly

[vstinner]

AMD64 Windows11 Refleaks 3.x build: https://buildbot.python.org/#/builders/920/builds/1141

FAIL: test_staggered_race_with_eager_tasks (test.test_asyncio.test_eager_task_factory.PyEagerTaskFactoryLoopTests.test_staggered_race_with_eager_tasks)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "b:\uildarea\3.x.ware-win11.refleak\build\Lib\test\test_asyncio\test_eager_task_factory.py", line 238, in test_staggered_race_with_eager_tasks
    self.run_coro(run())
    ~~~~~~~~~~~~~^^^^^^^
  File "b:\uildarea\3.x.ware-win11.refleak\build\Lib\test\test_asyncio\test_eager_task_factory.py", line 36, in run_coro
    return self.loop.run_until_complete(coro)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "b:\uildarea\3.x.ware-win11.refleak\build\Lib\asyncio\base_events.py", line 720, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
  File "b:\uildarea\3.x.ware-win11.refleak\build\Lib\asyncio\futures.py", line 198, in result
    raise self._exception.with_traceback(self._exception_tb)
  File "b:\uildarea\3.x.ware-win11.refleak\build\Lib\asyncio\tasks.py", line 289, in __step_run_and_handle_result
    result = coro.send(None)
  File "b:\uildarea\3.x.ware-win11.refleak\build\Lib\test\test_asyncio\test_eager_task_factory.py", line 232, in run
    self.assertEqual(winner, 'sleep1')
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
AssertionError: 'sleep2' != 'sleep1'
- sleep2
?      ^
+ sleep1
?      ^

I'm working on a fix.

Linked PRs

• gh-127258: Fix asyncio test_staggered_race_with_eager_tasks() #127259
• gh-127258: Fix asyncio test_staggered_race_with_eager_tasks() #127358
• [3.13] gh-127258: Fix asyncio test_staggered_race_with_eager_tasks() (GH-127358) #127401
• [3.12] gh-127258: Fix asyncio test_staggered_race_with_eager_tasks() (GH-127358) #127402

[ZeroIntensity]

I'm going to assume that this is related to one of the many staggered_race changes recently. We need to be very careful when changing it because we might give an unpleasant surprise to users of some older aiohttp versions.