Comment 0 for bug 1509077

2015-10-22 20:04:16 [-] 127.0.0.1 - - [22/Oct/2015:20:04:15 +0000] "POST /MAAS/api/1.0/nodes/node-81ec0a24-737c-11e5-b89b-00163e35cf93/?op=start HTTP/1.1" 500 66 "-" "Go 1.1 package http"
2015-10-22 20:04:18 [maasserver] ERROR: ################################ Exception: 'NoneType' object has no attribute 'get_managed_cluster_interface' ################################
2015-10-22 20:04:18 [maasserver] ERROR: Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/django/core/handlers/base.py", line 112, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/lib/python2.7/dist-packages/maasserver/utils/views.py", line 189, in view_atomic_with_post_commit_savepoint
    return view_atomic(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/django/db/transaction.py", line 339, in inner
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/maasserver/api/support.py", line 53, in __call__
    response = upcall(request, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/django/views/decorators/vary.py", line 19, in inner_func
    response = func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/piston/resource.py", line 167, in __call__
    result = self.error_handler(e, request, meth, em_format)
  File "/usr/lib/python2.7/dist-packages/piston/resource.py", line 165, in __call__
    result = meth(request, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/maasserver/api/support.py", line 201, in dispatch
    return function(self, request, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/maasserver/api/nodes.py", line 490, in start
    node.start(request.user, user_data=user_data, comment=comment)
  File "/usr/lib/python2.7/dist-packages/maasserver/utils/orm.py", line 464, in call_within_transaction
    return func_within_txn(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/django/db/transaction.py", line 339, in inner
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/maasserver/models/node.py", line 2316, in start
    return self._start(user, user_data)
  File "/usr/lib/python2.7/dist-packages/maasserver/utils/orm.py", line 464, in call_within_transaction
    return func_within_txn(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/django/db/transaction.py", line 339, in inner
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/maasserver/models/node.py", line 2356, in _start
    self.claim_auto_ips()
  File "/usr/lib/python2.7/dist-packages/maasserver/models/node.py", line 1998, in claim_auto_ips
    exclude_addresses=exclude_addresses)
  File "/usr/lib/python2.7/dist-packages/maasserver/models/interface.py", line 965, in claim_auto_ips
    auto_ip, exclude_addresses)
  File "/usr/lib/python2.7/dist-packages/maasserver/models/interface.py", line 977, in _claim_auto_ip
    ngi = subnet.get_managed_cluster_interface()
AttributeError: 'NoneType' object has no attribute 'get_managed_cluster_interface'