It looks like the changeset 0b99d7043a99 (issue #23694) introduced a regression:

http://buildbot.python.org/all/builders/x86%20Ubuntu%20Shared%203.x/builds/11358/

[340/393] test_multiprocessing_spawn
Timeout (1:00:00)!
Thread 0x55aacdc0 (most recent call first):
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/multiprocessing/connection.py", line 379 in _recv
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/multiprocessing/connection.py", line 407 in _recv_bytes
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/multiprocessing/connection.py", line 250 in recv
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/multiprocessing/managers.py", line 717 in _callmethod
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/multiprocessing/managers.py", line 943 in acquire
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/test/_test_multiprocessing.py", line 911 in test_notify_all
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/unittest/case.py", line 577 in run
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/unittest/case.py", line 625 in __call__
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/unittest/suite.py", line 122 in run
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/unittest/suite.py", line 84 in __call__
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/unittest/suite.py", line 122 in run
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/unittest/suite.py", line 84 in __call__
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/unittest/suite.py", line 122 in run
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/unittest/suite.py", line 84 in __call__
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/unittest/runner.py", line 176 in run
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/test/support/__init__.py", line 1772 in _run_suite
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/test/support/__init__.py", line 1806 in run_unittest
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/test/regrtest.py", line 1283 in test_runner
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/test/regrtest.py", line 1284 in runtest_inner
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/test/regrtest.py", line 967 in runtest
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/test/regrtest.py", line 763 in main
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/test/regrtest.py", line 1568 in main_in_temp_cwd
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/test/__main__.py", line 3 in <module>
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/runpy.py", line 85 in _run_code
  File "/srv/buildbot/buildarea/3.x.bolen-ubuntu/build/Lib/runpy.py", line 170 in _run_module_as_main
make: *** [buildbottest] Error 1