https://buildbot.python.org/all/#/builders/21/builds/2512

======================================================================
FAIL: test_logout (test.test_imaplib.RemoteIMAP_STARTTLSTest)
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Traceback (most recent call last):
  File "/home/dje/cpython-buildarea/3.x.edelsohn-rhel-z/build/Lib/test/test_imaplib.py", line 946, in test_logout
    self.assertEqual(rs[0], 'BYE')
AssertionError: 'NO' != 'BYE'
- NO
+ BYE


The logout() returns 'NO' if *any* exception is raised:

        try: typ, dat = self._simple_command('LOGOUT')
        except: typ, dat = 'NO', ['%s: %s' % sys.exc_info()[:2]]

Attached PR proposes a fix.