Comment 4 for bug 1535551

Reviewed: https://review.openstack.org/353263
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=247128b6c3c03f3c096af9c27a97badbae11e666
Submitter: Jenkins
Branch: master

commit 247128b6c3c03f3c096af9c27a97badbae11e666
Author: Kevin Benton <email address hidden>
Date: Fri Aug 5 14:44:10 2016 -0700

    Fix duplicate routerport handling

    Change 6281fdd introduced a try: except to catch
    a DuplicateError introduced by it's new constraint.
    However, the try moved it outside of the context manager
    so it broke the port cleanup logic.

    This patch completely eliminates the catch for the
    duplicate entry since we retry those anyway which
    would let the regular check see the duplication.

    This also adds a test to prevent another regression of
    being moved outside of the context manager.

    Related-Bug: #1535551
    Related-Bug: #1600344

    Change-Id: I5f473fff4f8372852d563c79dac2991089eb0b77