That looks like a similar example of the problem that bpo35378 solves. But the PR is merged and the test keeps failing:

test test_venv failed -- Traceback (most recent call last):
  File "/home/travis/build/python/cpython/Lib/test/test_venv.py", line 309, in test_multiprocessing
    out, err = check_output([envpy, '-c',
  File "/home/travis/build/python/cpython/Lib/test/test_venv.py", line 37, in check_output
    raise subprocess.CalledProcessError(
subprocess.CalledProcessError: Command '['/tmp/tmplplx90pf/bin/python', '-c', 'from multiprocessing import Pool; print(Pool(1).apply_async("Python".lower).get(3))']' died with <Signals.SIGABRT: 6>.

https://travis-ci.org/python/cpython/jobs/492305033


Running that command locally on master does not die with SIGABRT:

❯ ./python -c 'from multiprocessing import Pool; print(Pool(1).apply_async("Python".lower).get(3))'; echo $?
python
/home/pablogsal/github/cpython/Lib/multiprocessing/pool.py:234: ResourceWarning: unclosed running multiprocessing pool <multiprocessing.pool.Pool state=RUN pool_size=1>
  _warn(f"unclosed running multiprocessing pool {self!r}",
ResourceWarning: Enable tracemalloc to get the object allocation traceback
0