coverage.py 6.3 regression - SIGTERM hang during time.sleep()

[ben-spiller]

Describe the bug
I have a Python program that's doing a long (infinite) time.sleep(1000), and has no multiprocessing/threading. With coverage 6.2 it works but with 6.3 sending SIGTERM results in a hang.

To Reproduce

1. Python 3.10
2. coverage.py 6.3.0. 6.2.0 does not hang.
3. A python program that just does time.sleep(1000)
4. Sending a SIGTERM (on RHEL 8.5) does not terminate it with coverage.py 6.3 but does with 6.2.

Expected behavior
SIGTERM should still terminate the process - the presence of coverage.py shouldn't break that.

Additional context
Similar symptoms to GH-1310 but no multiprocessing involved here

[nedbat]

@ben-spiller Can you re-test with this fix for #1310 ?

pip install git+https://github.com/nedbat/coveragepy.git@803a5494ef23#egg=coverage

[nedbat]

Feel free to re-open this if you get more information.