nicira: net-gateway-create fails on neutron but succeeds on backend

[Salvatore Orlando]

If a gateway service is created, by mistake, with the same device, but two distinct interfaces, neutron fails with 500, but the service is sucessfully created on the backend.

Problems:

1) neutron should return 400, not 500
2) if the backend is successully configured, perhaps this is then a valid configuration and therefore neutron data constraints should be adjusted to take this into account

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/79804

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/79804
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=2014300886215452e5753529c68712d075cba57d
Submitter: Jenkins
Branch: master

commit 2014300886215452e5753529c68712d075cba57d
Author: Salvatore Orlando <email address hidden>
Date: Tue Mar 11 16:16:10 2014 -0700

    NSX: Allow multiple references to same gw device

    This patch amends a data model in order to allow user to specify
    the same gateway device multiple times in a network gateway
    specification.

    The corresponding migration is also being amended with this
    patch. This approach has been preferred to developing another
    migration since the migration being amended is still the most
    recent one for the NSX plugin.

    Change-Id: I4d24837d8d65fc45b838f3b616c9ec8a73a50d9c
    Closes-Bug: 1262790