TODO:

* Modify asyncio.unix_events._compute_returncode() to use waitstatus_to_exitcode(): need to update tests.
* Modify run_cgi() of http.server to log the exit code rather the exit status: use waitstatus_to_exitcode().
* Modify Tools/scripts/which.py to log the exit code using waitstatus_to_exitcode(): result of os.system('ls ' + longlist + ' ' + filename).
* Modify mailcap.test() to use waitstatus_to_exitcode(): os.system(command).
* Fix CI to get PR 19277 and PR 19278 merged.
* Decide if subprocess should reject WIFSTOPPED() or not.
* Check if the pure Python implementation of os._spawnvef() handles WIFSTOPPED() properly.
* Maybe implement timeout on Windows for test.support.wait_process().


Eryk Sun:
> FWIW, I wouldn't recommend relying on os.waitpid to get the correct process exit status in Windows. Status codes are 32 bits and generally all bits are required.

I created bpo-40138 "Windows implementation of os.waitpid() truncates the exit status (status << 8)".