improve isolation of test_pending_call_creates_thread_subinterpreter

[kumaraditya303]

For better isolation from the current runtime, run the test in a separate subprocess similarly to test_pending_call_creates_thread.

[bedevere-bot]

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[ZeroIntensity]

I'm not sure I understand the rationale here. We already have a test for doing this in a subprocess: test_pending_call_creates_thread.

[kumaraditya303]

I'm not sure I understand the rationale here. We already have a test for doing this in a subprocess: test_pending_call_creates_thread.

Yes, but that runs in main interpreter but this runs in a sub-interpreter.

[ZeroIntensity]

But why do it in a subprocess? We create and destroy subinterpreters in the main process in other tests, don't we?