Duplicated notification when pooling enabled

[Feilong Wang]

When pooling enabled, both the subscription controller of pooling and storage backend will be added in the pipeline. As a result, when there is a new message posted, the notification will be triggered two times.

[Flavio Percoco (flaper87)]

https://review.openstack.org/#/c/218072/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/218072
Committed: https://git.openstack.org/cgit/openstack/zaqar/commit/?id=381ec2569813ba2fbd63183737a0341ecae38c5f
Submitter: Jenkins
Branch: master

commit 381ec2569813ba2fbd63183737a0341ecae38c5f
Author: Fei Long Wang <email address hidden>
Date: Fri Aug 28 15:17:59 2015 +1200

    Fix duplicated notification

    Now when the pooling is enabled, notification will be triggered two
    times because the subscription controller of pooling is also in the
    pipeline. This patch fixes it by checking the subscription controller
    type.

    Closes-Bug: #1489686

    Change-Id: I55c72e3869e9b0490bcab3bcae571946bda65aa5