gh-115490: Work around test.support.interpreters.channels not handling unloading

[Yhg1s]

Work around test.support.interpreters.channels not handling unloading, which regrtest does when running tests sequentially, by explicitly skipping the unloads of test.support.interpreters and its submodules.

This can be rolled back once test.support.interpreters.channels supports unloading, if we are keeping sequential runs in the same process around.

• Issue: test_interpreters fails when running tests sequentially #115490

[vstinner]

LGTM.

@ericsnowcurrently: test_interpreters should do something about that in a tearDownModule() function, or find a workaround, rather than having to use such hack in regrtest :-(

I approve this PR to unblock Python 3.13 alpha4 release.

cc @serhiy-storchaka

[vstinner]

@ericsnowcurrently: Is Python 3.12 affected?

[Yhg1s]

No. test_interpreters.test_channels doesn't exist in 3.12, and running test_interpreters twice in the same process doesn't show any issues:

./python -m test test_interpreters test_interpreters
Using random seed: 531474967
0:00:00 load avg: 2.24 Run 2 tests sequentially
0:00:00 load avg: 2.24 [1/2] test_interpreters
0:00:03 load avg: 2.06 [2/2] test_interpreters
== Tests result: SUCCESS ==
All 2 tests OK.

[encukou]

test_interpreters should do something about that in a tearDownModule() function

For the record, that fix is here: #115493

[vstinner]

No. test_interpreters.test_channels doesn't exist in 3.12, and running test_interpreters twice in the same process doesn't show any issues:

Thanks for the confirmation.