The test failed on s390x Debian 3.x but then passed when run again.

http://buildbot.python.org/all/builders/s390x%20Debian%203.x/builds/868/steps/test/logs/stdio

0:07:58 load avg: 1.15 [286/406/1] test_imaplib failed -- running: test_multiprocessing_spawn (76 sec)
...
test_logincapa (test.test_imaplib.RemoteIMAPTest) ... ok
test_logout (test.test_imaplib.RemoteIMAPTest) ... ok
test_logincapa (test.test_imaplib.RemoteIMAP_SSLTest) ... ok
test_logincapa_with_client_certfile (test.test_imaplib.RemoteIMAP_SSLTest) ... skipped "bpo-30175: FIXME: cyrus.andrew.cmu.edu doesn't accept our randomly generated client x509 certificate anymore"
test_logincapa_with_client_ssl_context (test.test_imaplib.RemoteIMAP_SSLTest) ... skipped "bpo-30175: FIXME: cyrus.andrew.cmu.edu doesn't accept our randomly generated client x509 certificate anymore"
test_logout (test.test_imaplib.RemoteIMAP_SSLTest) ... ok
test_ssl_context_certfile_exclusive (test.test_imaplib.RemoteIMAP_SSLTest) ... ok
test_ssl_context_keyfile_exclusive (test.test_imaplib.RemoteIMAP_SSLTest) ... ok
test_logincapa (test.test_imaplib.RemoteIMAP_STARTTLSTest) ... ok
test_logout (test.test_imaplib.RemoteIMAP_STARTTLSTest) ... FAIL
...
======================================================================
FAIL: test_logout (test.test_imaplib.RemoteIMAP_STARTTLSTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.x.edelsohn-debian-z/build/Lib/test/test_imaplib.py", line 916, in test_logout
    self.assertEqual(rs[0], 'BYE')
AssertionError: 'NO' != 'BYE'
- NO
+ BYE

(...)

Re-running test 'test_imaplib' in verbose mode
(...)
Ran 95 tests in 15.863s
OK (skipped=2)