Question: why faulthandler didn't kill the test after 15 min? .github/appveyor.yml runs the test suite using --timeout=1200. Extract of logs:
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PCbuild\rt.bat -q -uall -u-cpu -u-largefile -rwW --slowest --timeout=1200 --fail-env-changed -j0
C:\projects\cpython>"C:\projects\cpython\PCbuild\win32\python.exe"  -u -Wd -E -bb -m test  -uall -u-cpu -u-largefile -rwW --slowest --timeout 1200 --fail-env-changed -j0 
== CPython 3.7.1rc2+ (a4ccd9402d:a4ccd9402d, Oct 17 2018, 23:09:59) [MSC v.1915 32 bit (Intel)]
== Windows-10-10.0.14393-SP0 little-endian
== cwd: C:\projects\cpython\build\test_python_4988
== CPU count: 2
== encodings: locale=cp1252, FS=utf-8
Using random seed 7230291
Run tests in parallel using 4 child processes
0:00:00 [  1/416] test_wait4 skipped
test_wait4 skipped -- object <module 'os' from 'C:\\projects\\cpython\\lib\\os.py'> has no attribute 'fork'
0:00:00 [  2/416] test_augassign passed
(...)
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See also bpo-34714 and "timeout in test_multiprocessing_spawn x86 Windows7 3.x buildbot" and bpo-34513: "test_multiprocessing_spawn fails on x86 Windows7 3.7 buildbot".