Comment 0 for bug 1549750

Not sure if it affects our normal deployment, it affects at least our UI func tests.

Some examples:

https://ci.fuel-infra.org/job/verify-fuel-web-ui/9080/
https://ci.fuel-infra.org/job/verify-fuel-web-ui/9086/

In app.log from artifacts you can see tracebacks like

Exception in thread EXECUTE_TASKS:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner
    self.run()
  File "/home/jenkins/workspace/verify-fuel-web-ui/nailgun/nailgun/task/fake.py", line 285, in run
    self.notify(msg)
  File "/home/jenkins/workspace/verify-fuel-web-ui/nailgun/nailgun/task/fake.py", line 202, in notify
    resp_method(**kwargs)
  File "/home/jenkins/workspace/verify-fuel-web-ui/nailgun/nailgun/rpc/receiver.py", line 230, in remove_images_resp
    objects.Task.update(task, {'status': status})
  File "/home/jenkins/workspace/verify-fuel-web-ui/nailgun/nailgun/objects/task.py", line 268, in update
    logger.debug("Updating task: %s", instance.uuid)
AttributeError: 'NoneType' object has no attribute 'uuid'

or

2016-02-25 10:10:47.434 ERROR [7fe4eb25e700] (manager) Traceback (most recent call last):
  File "/home/jenkins/workspace/verify-fuel-web-ui/nailgun/nailgun/task/manager.py", line 57, in _call_silently
    to_return = method(task, *args, **kwargs)
  File "/home/jenkins/workspace/verify-fuel-web-ui/nailgun/nailgun/task/task.py", line 1537, in execute
    'settings': conf or cls.conf()
  File "/home/jenkins/workspace/verify-fuel-web-ui/nailgun/nailgun/task/task.py", line 1476, in conf
    editable_attrs = node.cluster.attributes['editable']
AttributeError: 'NoneType' object has no attribute 'attributes'