host-scheduler on chromeos-server118 is dying/respawning
repeatedly.  Here's the exception:

Traceback (most recent call last):
  File "/usr/local/autotest/scheduler/host_scheduler.py", line 520, in <module>
    main()
  File "/usr/local/autotest/scheduler/host_scheduler.py", line 499, in main
    host_scheduler.tick()
  File "/usr/local/autotest/site-packages/chromite/lib/metrics.py", line 483, in wrapper
    return fn(*args, **kwargs)
  File "/usr/local/autotest/scheduler/host_scheduler.py", line 392, in tick
    self._schedule_jobs()
  File "/usr/local/autotest/site-packages/chromite/lib/metrics.py", line 483, in wrapper
    return fn(*args, **kwargs)
  File "/usr/local/autotest/scheduler/host_scheduler.py", line 333, in _schedule_jobs
    for acquisition in self.find_hosts_for_jobs(unverified_host_jobs):
  File "/usr/local/autotest/scheduler/host_scheduler.py", line 282, in find_hosts_for_jobs
    for host, job in zip(hosts, host_jobs):
  File "/usr/local/autotest/scheduler/rdb_lib.py", line 79, in acquire_hosts
    job_query_manager = JobQueryManager(queue_entries, suite_min_duts)
  File "/usr/local/autotest/scheduler/rdb_lib.py", line 34, in __init__
    self._labels = self.query_manager._get_labels(self._job_deps)
  File "/usr/local/autotest/site-packages/chromite/lib/metrics.py", line 483, in wrapper
    return fn(*args, **kwargs)
  File "/usr/local/autotest/scheduler/query_managers.py", line 393, in _get_labels
    where="id IN (%s)" % job_string_label_list)
  File "/usr/local/autotest/scheduler/scheduler_models.py", line 329, in fetch
    return [cls(id=row[0], row=row) for row in rows]
  File "/usr/local/autotest/scheduler/scheduler_models.py", line 169, in __init__
    self._update_fields_from_row(row)
  File "/usr/local/autotest/scheduler/scheduler_models.py", line 227, in _update_fields_from_row
    self._assert_row_length(row)
  File "/usr/local/autotest/scheduler/scheduler_models.py", line 192, in _assert_row_length
    self.__table, row, len(row), self._fields, len(self._fields)))
AssertionError: table = afe_labels, row = (210L, u'pool:bvt', u'', 0, 0, 0, None, 0)/8, fields = ('id', 'name', 'kernel_config', 'platform', 'invalid', 'only_if_needed', 'atomic_group_id')/7