If found this error in system tests - looks like wrong assert - code should check
if disk is not None before checking state.
I'm not sure who is the owner of this test, so posting here.
08:28:05   # snapshots_merge: 
08:28:31 Unhandled exception in <function <lambda> at 0x276a5f0>
08:28:31 Traceback (most recent call last):
08:28:31   File "/usr/lib/python2.7/site-packages/ovirtlago/testlib.py", line 217, in assert_equals_within
08:28:31     res = func()
08:28:31   File "/home/jenkins/workspace/ovirt-system-tests_manual/ovirt-system-tests/basic-suite-master/test-scenarios/004_basic_sanity.py", line 466, in <lambda>
08:28:31     api.vms.get(VM0_NAME).disks.get(disk_name).status.state == 'ok'
08:28:31 AttributeError: 'NoneType' object has no attribute 'state'
08:28:31 Error while running thread
08:28:31 Traceback (most recent call last):
08:28:31   File "/usr/lib/python2.7/site-packages/lago/utils.py", line 57, in _ret_via_queue
08:28:31     queue.put({'return': func()})
08:28:31   File "/home/jenkins/workspace/ovirt-system-tests_manual/ovirt-system-tests/basic-suite-master/test-scenarios/004_basic_sanity.py", line 465, in snapshot_live_merge
08:28:31     lambda:
08:28:31   File "/usr/lib/python2.7/site-packages/ovirtlago/testlib.py", line 264, in assert_true_within_long
08:28:31     assert_equals_within_long(func, True, allowed_exceptions)
08:28:31   File "/usr/lib/python2.7/site-packages/ovirtlago/testlib.py", line 251, in assert_equals_within_long
08:28:31     func, value, LONG_TIMEOUT, allowed_exceptions=allowed_exceptions
08:28:31   File "/usr/lib/python2.7/site-packages/ovirtlago/testlib.py", line 217, in assert_equals_within
08:28:31     res = func()
08:28:31   File "/home/jenkins/workspace/ovirt-system-tests_manual/ovirt-system-tests/basic-suite-master/test-scenarios/004_basic_sanity.py", line 466, in <lambda>
08:28:31     api.vms.get(VM0_NAME).disks.get(disk_name).status.state == 'ok'
08:28:31 AttributeError: 'NoneType' object has no attribute 'state'