from https://pantheon.corp.google.com/storage/browser/chromeos-autotest-results/hosts/chromeos4-row2-rack8-host5/55679529-repair/

05/23 04:34:56.278 ERROR|            repair:0397| Repair failed: Re-install the stable build via AU
Traceback (most recent call last):
  File "/usr/local/autotest/client/common_lib/hosts/repair.py", line 395, in _repair_host
    self.repair(host)
  File "/usr/local/autotest/server/hosts/cros_repair.py", line 297, in repair
    afe_utils.machine_install_and_update_labels(host, repair=True)
  File "/usr/local/autotest/server/afe_utils.py", line 190, in machine_install_and_update_labels
    image_name, host_attributes = host.machine_install(*args, **dargs)
  File "/usr/local/autotest/server/hosts/cros_host.py", line 694, in machine_install
    update_url, devserver = self._stage_image_for_update()
  File "/usr/local/autotest/server/hosts/cros_host.py", line 595, in _stage_image_for_update
    image_name = self.get_repair_image_name()
  File "/usr/local/autotest/server/hosts/cros_host.py", line 351, in get_repair_image_name
    raise error.AutoservError('DUT has no board attribute, '
AutoservError: DUT has no board attribute, cannot be repaired.

The repair failed because it looks like either the board label wasn't there or there was a problem getting the labels from the AFE.  

In any case, I reverified the host, it went through the repair process again and passed so filing this more as an fyi and for posterity.

reverify that failed (missing python):
http://cautotest/tko/retrieve_logs.cgi?job=/results/hosts/chromeos4-row2-rack8-host5/55686892-verify

passing repair:
https://pantheon.corp.google.com/storage/browser/chromeos-autotest-results/hosts/chromeos4-row2-rack8-host5/55686991-repair