Comment 8 for bug 1514810

Reviewed: https://review.openstack.org/249060
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=b2801195e3b3202290f55d261c89d304b2a4a0fd
Submitter: Jenkins
Branch: stable/liberty

commit b2801195e3b3202290f55d261c89d304b2a4a0fd
Author: Gary Kotton <email address hidden>
Date: Wed Nov 18 08:26:18 2015 -0800

    IPAM: fix 'enable-dhcp' with internal driver

    Commit 0c1f96ad5a6606c1205bd50ea944c3a383892cde broke the ipam
    internal driver. The base plugin should only call the ipam interface
    and not invoke the IPallocation data model.

    The code that validated that the subnet had one free IP address was
    removed. This would not guarantee that a port would indeed be free,
    that is, a parallel operation could have created a port on the subnet
    during this check.

    Closes-bug: #1514810

    Conflicts:
     neutron/db/db_base_plugin_v2.py

    Change-Id: I4d7ecb985762a8eef39cb2f22f210b4899f1a22e
    (cherry picked from commit 8d8444aa0ce0e6db1ebbc922311ec1eef546f2fe)