2016-03-11 14:57:52 [maasserver] ERROR: ################################ Exception: 'NoneType' object has no attribute 'url' ################################
2016-03-11 14:57:52 [maasserver] ERROR: Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/django/core/handlers/base.py", line 132, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/lib/python3/dist-packages/maasserver/utils/views.py", line 180, in view_atomic_with_post_commit_savepoint
    return view_atomic(*args, **kwargs)
  File "/usr/lib/python3.5/contextlib.py", line 30, in inner
    return func(*args, **kwds)
  File "/usr/lib/python3/dist-packages/maasserver/api/pxeconfig.py", line 202, in pxeconfig
    preseed_url = compose_preseed_url(node)
  File "/usr/lib/python3/dist-packages/maasserver/preseed.py", line 704, in compose_preseed_url
    base_url = node.get_boot_primary_rack_controller().url
AttributeError: 'NoneType' object has no attribute 'url'