In Vlan mode can't create a network with ---vlan option

[Alvaro Lopez]

When I try to create a network specifying a Vlan, nova fails:

    $ nova network-create --fixed-range-v4 172.16.10.0/24 --vlan 2010 --private
    ERROR: The server has either erred or is incapable of performing the requested operation. (HTTP 500) (Request-ID: req-ed9ea8c3-2fbe-49e2-8383-3da2acc8baeb)

And the log shows a DuplicateVlan exception, since in tries to use my
vlan_start config option:

    DuplicateVlan: Detected existing vlan with id 2000

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/34529
Committed: http://github.com/openstack/nova/commit/ec4a9490047106b36c8a6bdf91fc7579b84868dd
Submitter: Jenkins
Branch: master

commit ec4a9490047106b36c8a6bdf91fc7579b84868dd
Author: Alvaro Lopez Garcia <email address hidden>
Date: Wed Jul 17 13:20:33 2013 +0200

    Fix network creation in Vlan mode

    - If "vlan" is specified when creating a network, we honour the option.
    - If it is not specified, the Vlan number is calculated as follows:
    CONF.vlan_start + num_existing_networks + index_of_requested_network
    - If the above vlan is in use, try to get the next free vlan.

    Fixes bug 1194835
    Fixes bug 1169026

    Change-Id: Id4476c14f9dadcf498a499534337477b3f64f604