[vankudothuadhinaik]

On macOS, Popen._wait_kqueue() catches OSError from kqueue.control() and falls back to polling. Since InterruptedError is an OSError subclass, this can swallow an exception raised by a Python signal handler instead of propagating it.

Explicitly re-raise InterruptedError while preserving fallback polling for other OSError failures. Add a kqueue-specific regression test.

Validation performed:

• git diff --check: passed.
• Focused kqueue regression: not run; the available Windows environment does not support kqueue and lacked a suitable checkout-built interpreter.
• Native macOS testing: not performed.

The macOS-specific regression still needs validation in CPython CI.

• Issue: subprocess.run(timeout=...) swallows a signal handler's InterruptedError on macOS in Python 3.15 #160700

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[NikitaMikhailov]

LGTM. I tested the code at 95bcfc0 on macOS with a locally built debug interpreter:

• The new regression test fails without the fix and passes with it, including 100 consecutive runs.
• The full test_subprocess suite passes: 372 tests run, 54 skipped.
• A separate reproducer using a real SIGALRM whose handler raises InterruptedError passes on five consecutive runs.

The change preserves the fallback for other OSError exceptions and the existing kqueue cleanup in finally.

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