Just saw this on[1]:
2017-12-28 10:09:24,980-0500 INFO  (MainThread) [vdsm.api] FINISH prepareForShutdown return=None from=internal, task_id=1a83a4d3-43e3-4833-883b-dfd2fe4d76be (api:52)
2017-12-28 10:09:24,980-0500 INFO  (MainThread) [vds] Stopping threads (vdsmd:159)
2017-12-28 10:09:24,980-0500 INFO  (MainThread) [vds] Exiting (vdsmd:170)
2017-12-28 10:09:25,011-0500 INFO  (mailbox-hsm) [storage.MailBox.HsmMailMonitor] HSM_MailboxMonitor - Incoming mail monitoring thread stopped, clearing outgoing mail (mailbox:511)
2017-12-28 10:09:25,011-0500 INFO  (mailbox-hsm) [storage.MailBox.HsmMailMonitor] HSM_MailMonitor sending mail to SPM - ['/usr/bin/dd', 'of=/rhev/data-center/9b97451a-0312-4c69-85e2-f86d6d273636/mastersd/dom_md/inbox', 'iflag=fullblock', 'oflag=direct', 'conv=notrunc', 'bs=4096', 'count=1', 'seek=1'] (mailbox:387)
2017-12-28 10:09:25,012-0500 ERROR (mailbox-hsm) [storage.MailBox.HsmMailMonitor] FINISH thread <Thread(mailbox-hsm, started daemon 139968009594624)> failed (concurrent:201)
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/vdsm/common/concurrent.py", line 194, in run
    ret = func(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/vdsm/storage/mailbox.py", line 514, in _run
    self._sendMail()  # Clear outgoing mailbox
  File "/usr/lib/python2.7/site-packages/vdsm/storage/mailbox.py", line 394, in _sendMail
    _mboxExecCmd(self._outCmd, data=self._outgoingMail)
  File "/usr/lib/python2.7/site-packages/vdsm/storage/mailbox.py", line 84, in _mboxExecCmd
    return misc.execCmd(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/vdsm/common/commands.py", line 53, in execCmd
    command = cmdutils.wrap_command(command, with_ioclass=ioclass,
AttributeError: 'NoneType' object has no attribute 'wrap_command'
2017-12-28 10:09:28,965-0500 INFO  (MainThread) [vds] (PID: 23232) I am the actual vdsm 4.20.9-84.git615770f.el7.centos lago-basic-suite-master-host-0 (3.10.0-693.2.2.el7.x86_64) (vdsmd:148)
2017-12-28 10:09:28,966-0500 INFO  (MainThread) [vds] VDSM will run with cpu affinity: frozenset([1]) (vdsmd:254)
2017-12-28 10:09:28,970-0500 INFO  (MainThread) [storage.HSM] START HSM init (hsm:366)


[1] http://jenkins.ovirt.org/job/ovirt-system-tests_master_check-patch-el7-x86_64/3113/artifact/exported-artifacts/basic-suite-master__logs/test_logs/basic-suite-master/post-005_network_by_label.py/lago-basic-suite-master-host-0/_var_log/vdsm/vdsm.log