test_multiprocessing_fork fails only if run all tests on FreeBSD. It is passed successfully if run it separately.

$ ./python -m test -vuall
...
======================================================================
FAIL: test_many_processes (test.test_multiprocessing_fork.WithProcessesTestProcess)
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Traceback (most recent call last):
  File "/usr/home/serhiy/py/cpython3.7-debug/Lib/test/_test_multiprocessing.py", line 505, in test_many_processes
    self.assertEqual(p.exitcode, -signal.SIGTERM)
AssertionError: 1 != -15

======================================================================
FAIL: test_terminate (test.test_multiprocessing_fork.WithProcessesTestProcess)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/home/serhiy/py/cpython3.7-debug/Lib/test/_test_multiprocessing.py", line 360, in test_terminate
    self.assertEqual(exitcode, -signal.SIGTERM)
AssertionError: 1 != -15

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test_subprocess hangs, perhaps due to the same cause.