I managed to reproduce the failure in 50 seconds using the command:

$ ./python -m test test_epoll -F -v -j20
(...)
0:00:49 load avg: 4.81 [257/1] test_epoll failed
test_add (test.test_epoll.TestEPoll) ... ok
test_badcreate (test.test_epoll.TestEPoll) ... ok
test_close (test.test_epoll.TestEPoll) ... ok
test_context_manager (test.test_epoll.TestEPoll) ... ok
test_control_and_wait (test.test_epoll.TestEPoll) ... FAIL
test_create (test.test_epoll.TestEPoll) ... ok
test_errors (test.test_epoll.TestEPoll) ... ok
test_fd_non_inheritable (test.test_epoll.TestEPoll) ... ok
test_fromfd (test.test_epoll.TestEPoll) ... ok
test_unregister_closed (test.test_epoll.TestEPoll) ... ok

======================================================================
FAIL: test_control_and_wait (test.test_epoll.TestEPoll)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/vstinner/python/master/Lib/test/test_epoll.py", line 199, in test_control_and_wait
    self.assertEqual(events, expected)
AssertionError: Lists differ: [(5, 5)] != [(4, 5), (5, 5)]

First differing element 0:
(5, 5)
(4, 5)

Second list contains 1 additional elements.
First extra element 1:
(5, 5)

- [(5, 5)]
+ [(4, 5), (5, 5)]

----------------------------------------------------------------------

Ran 10 tests in 2.120s

FAILED (failures=1)
test test_epoll failed
(...)
Total duration: 49.3 sec
Tests result: FAILURE