gh-140438: Properly run the asyncio REPL in REPL tests

[bswck]

Mixing -i with -m asyncio first spawns the asyncio REPL. After asyncio REPL exits, it spawns the regular Python REPL.

Here we're introducing more idiomatic way to test other custom REPLs in test_repl as necessary, without needing a pseudo-terminal.

CC @ZeroIntensity (mentorship): skip issue, skip news, needs backport to 3.13, needs backport to 3.14.

• Issue: The -i flag is mixed with custom REPLs in tests #140438

[ZeroIntensity]

I think it would be good if you created an issue for this.

[bswck]

I think it would be good if you created an issue for this.

@ZeroIntensity done; let's remove the skip issue label now so that the bot can do its job.

[bswck]

cc @asvetlov

[ZeroIntensity]

@kumaraditya303 is our primary asyncio maintainer at the moment. Kumar, are you familiar enough with the asyncio REPL to review this?

[kumaraditya303]

LGTM

[miss-islington-app]

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

[bedevere-app]

GH-140507 is a backport of this pull request to the 3.14 branch.

[bedevere-app]

GH-140508 is a backport of this pull request to the 3.13 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM64 MacOS M1 Refleaks NoGIL 3.13 (tier-2) has failed when building commit adf0c11.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1396/builds/1697) and take a look at the build logs.
4. Check if the failure is related to this commit (adf0c11) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1396/builds/1697

Failed tests:

• test.test_multiprocessing_forkserver.test_processes

Failed subtests:

• test_repr_rlock - test.test_multiprocessing_forkserver.test_processes.WithProcessesTestLock.test_repr_rlock

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.13.itamaro-macos-arm64-aws.macos-with-brew.refleak.nogil/build/Lib/test/_test_multiprocessing.py", line 1492, in test_repr_rlock
    self.assertEqual('<RLock(SomeOtherThread, nonzero)>', repr(lock))
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: '<RLock(SomeOtherThread, nonzero)>' != '<RLock(None, 0)>'
- <RLock(SomeOtherThread, nonzero)>
+ <RLock(None, 0)>