When regrtest is used with -jN, regrtest spawn child processes to run tests. If a child crashs, regrtest master process immedialtely fails. It would prefer to be able to continue to run following tests. It's not because a single test crashed that all tests would crash.

Example of output when a crash occurs:
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(...)
0:02:45 [118/404/3] test_bytes crashed -- running: test_multiprocessing_spawn (67 sec), test_io (54 sec), test_subprocess (76 sec)
python: Objects/abstract.c:2186: _Py_CheckFunctionResult: Assertion `(callable != NULL) ^ (where != NULL)' failed.
Fatal Python error: Aborted

Current thread 0x00007f9210f11440 (most recent call first):
  File "/home/haypo/prog/python/git_cpython/Lib/unittest/case.py", line 177 in handle
  File "/home/haypo/prog/python/git_cpython/Lib/unittest/case.py", line 728 in assertRaises
  File "/home/haypo/prog/python/git_cpython/Lib/test/test_bytes.py", line 636 in test_maketrans
  (...)
  File "/home/haypo/prog/python/git_cpython/Lib/runpy.py", line 85 in _run_code
  File "/home/haypo/prog/python/git_cpython/Lib/runpy.py", line 193 in _run_module_as_main

Traceback (most recent call last):
  File "/home/haypo/prog/python/git_cpython/Lib/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  (...)
  File "/home/haypo/prog/python/git_cpython/Lib/test/libregrtest/main.py", line 411, in run_tests
    run_tests_multiprocess(self)
  File "/home/haypo/prog/python/git_cpython/Lib/test/libregrtest/runtest_mp.py", line 221, in run_tests_multiprocess
    raise Exception(msg)
Exception: Child error on test_bytes: Exit code -6
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