gh-119710: Let asyncio Process.wait() finish on only process exit.

[tapetersen]

gh-119710: Let asyncio Process.wait() finish on only process exit

Letting Process.wait() only wait on actual process return is closer to how it's documented and consistent with Popen.wait(). This also reduces complexity for waking waiters which was inconsistend depending on ordering of wait/exit.

[python-cla-bot]

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[kumaraditya303]

I simplified the added test and also fixed it, now it correctly fails on main branch but passes on this. here's the failure on windows:

======================================================================ERROR: test_wait_even_if_pipe_is_open (test.test_asyncio.test_subprocess.SubprocessProactorTests.test_wait_even_if_pipe_is_open)----------------------------------------------------------------------Traceback (most recent call last): File "D:\cpython\Lib\asyncio\tasks.py", line 488, in wait_for return await fut ^^^^^^^^^ File "D:\cpython\Lib\asyncio\subprocess.py", line 137, in wait return await self._transport._wait() ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "D:\cpython\Lib\asyncio\base_subprocess.py", line 255, in _wait return await waiter ^^^^^^^^^^^^asyncio.exceptions.CancelledErrorThe above exception was the direct cause of the following exception:Traceback (most recent call last): File "D:\cpython\Lib\test\test_asyncio\test_subprocess.py", line 446, in test_wait_even_if_pipe_is_open self.loop.run_until_complete(run()) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^ File "D:\cpython\Lib\asyncio\base_events.py", line 725, in run_until_complete return future.result() ~~~~~~~~~~~~~^^ File "D:\cpython\Lib\test\test_asyncio\test_subprocess.py", line 436, in run returncode = await asyncio.wait_for( ^^^^^^^^^^^^^^^^^^^^^^^ wait_proc, timeout=support.SHORT_TIMEOUT) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "D:\cpython\Lib\asyncio\tasks.py", line 487, in wait_for async with timeouts.timeout(timeout): ~~~~~~~~~~~~~~~~^^^^^^^^^ File "D:\cpython\Lib\asyncio\timeouts.py", line 115, in __aexit__ raise TimeoutError from exc_valTimeoutError----------------------------------------------------------------------Ran 41 tests in 35.871s

[miss-islington-app]

Thanks @tapetersen for the PR, and @kumaraditya303 for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14, 3.15.
🐍🍒⛏🤖

[bedevere-app]

GH-154170 is a backport of this pull request to the 3.15 branch.

[bedevere-app]

GH-154171 is a backport of this pull request to the 3.14 branch.

[bedevere-app]

GH-154172 is a backport of this pull request to the 3.13 branch.

[tapetersen]

@kumaraditya303 Thanks for the review and windows fix.