Indeed. According to the log[*], the failure occurs during attach storage domain procedure, which is not related to imageio.
File "/home/jenkins/workspace/ovirt-4.2_change-queue-tester/ovirt-system-tests/basic-suite-4.2/test-scenarios/007_sd_reattach.py", line 83, in reattach_storage_domain
dc.storage_domains_service().add(sd)
File "/usr/lib64/python2.7/site-packages/ovirtsdk4/services.py", line 2944, in add
return self._internal_add(storage_domain, headers, query, wait)
File "/usr/lib64/python2.7/site-packages/ovirtsdk4/service.py", line 232, in _internal_add
return future.wait() if wait else future
File "/usr/lib64/python2.7/site-packages/ovirtsdk4/service.py", line 55, in wait
return self._code(response)
File "/usr/lib64/python2.7/site-packages/ovirtsdk4/service.py", line 229, in callback
self._check_fault(response)
File "/usr/lib64/python2.7/site-packages/ovirtsdk4/service.py", line 132, in _check_fault
self._raise_error(response, body)
File "/usr/lib64/python2.7/site-packages/ovirtsdk4/service.py", line 118, in _raise_error
raise error
Error: Fault reason is "Operation Failed". Fault detail is "[Network error during communication with the Host.]". HTTP response code is 400.