Comment 3 for bug 1348664

Interesting:

we experience this problem even if we have empty list of networks.

root@node-1:~# nova-manage network list
id IPv4 IPv6 start address DNS1 DNS2 VlanID project uuid
No networks found
root@node-1:~# /usr/bin/nova-manage network create novanetwork 10.0.0.0/16 8 32 --dns2 8.8.8.8 --vlan 103 --dns1 8.8.4.4
2014-07-26 08:59:09.356 31454 INFO nova.network.driver [-] Loading network driver 'nova.network.linux_net'
2014-07-26 08:59:09.357 31454 DEBUG nova.servicegroup.api [-] ServiceGroup driver defined as an instance of db __new__ /usr/lib/python2.7/dist-packages/nova/servicegroup/api.py:65
2014-07-26 08:59:09.401 31454 DEBUG stevedore.extension [-] found extension EntryPoint.parse('file = nova.image.download.file') _load_plugins /usr/lib/python2.7/dist-packages/stevedore/extension.py:156
2014-07-26 08:59:09.412 31454 DEBUG stevedore.extension [-] found extension EntryPoint.parse('file = nova.image.download.file') _load_plugins /usr/lib/python2.7/dist-packages/stevedore/extension.py:156
/usr/lib/python2.7/dist-packages/nova/openstack/common/db/sqlalchemy/session.py:379: DeprecationWarning: BaseException.message has been deprecated as of Python 2.6
  match = pattern.match(integrity_error.message)
Command failed, please check log for more info
2014-07-26 08:59:09.733 31454 CRITICAL nova [req-57790599-5bf4-4c18-9fc6-c81d12a889d1 None] DuplicateVlan: Detected existing vlan with id 103
2014-07-26 08:59:09.733 31454 TRACE nova Traceback (most recent call last):
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/bin/nova-manage", line 10, in <module>
2014-07-26 08:59:09.733 31454 TRACE nova sys.exit(main())
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/cmd/manage.py", line 1376, in main
2014-07-26 08:59:09.733 31454 TRACE nova ret = fn(*fn_args, **fn_kwargs)
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/cmd/manage.py", line 530, in create
2014-07-26 08:59:09.733 31454 TRACE nova net_manager.create_networks(context.get_admin_context(), **kwargs)
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/network/manager.py", line 1865, in create_networks
2014-07-26 08:59:09.733 31454 TRACE nova self, context, vpn=True, **kwargs)
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/network/manager.py", line 1094, in create_networks
2014-07-26 08:59:09.733 31454 TRACE nova return self._do_create_networks(context, **kwargs)
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/network/manager.py", line 1232, in _do_create_networks
2014-07-26 08:59:09.733 31454 TRACE nova net.create()
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/objects/base.py", line 151, in wrapper
2014-07-26 08:59:09.733 31454 TRACE nova return fn(self, ctxt, *args, **kwargs)
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/objects/network.py", line 131, in create
2014-07-26 08:59:09.733 31454 TRACE nova db_network = db.network_create_safe(context, updates)
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/db/api.py", line 929, in network_create_safe
2014-07-26 08:59:09.733 31454 TRACE nova return IMPL.network_create_safe(context, values)
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 146, in wrapper
2014-07-26 08:59:09.733 31454 TRACE nova return f(*args, **kwargs)
2014-07-26 08:59:09.733 31454 TRACE nova File "/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.py", line 2519, in network_create_safe
2014-07-26 08:59:09.733 31454 TRACE nova raise exception.DuplicateVlan(vlan=values['vlan'])
2014-07-26 08:59:09.733 31454 TRACE nova DuplicateVlan: Detected existing vlan with id 103
2014-07-26 08:59:09.733 31454 TRACE nova