Comment 4 for bug 1563070

Reviewed: https://review.openstack.org/305693
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=93795a4bda47605d5616476b2a456772308aa3c3
Submitter: Jenkins
Branch: stable/mitaka

commit 93795a4bda47605d5616476b2a456772308aa3c3
Author: Kevin Benton <email address hidden>
Date: Mon Mar 28 14:14:15 2016 -0700

    Fix deprecation warning for external_network_bridge

    We only want this to warn when a deployer has set anything other
    than a blank string. The olso cfg would warn whenever it was set
    so it was incorrectly warning on the value we want operators to
    set it to.

    This changes the cfg option to not use deprecated for removal and
    the L3 agent config validation to emit a warning if its not set
    to the value we are suggesting.

    Change-Id: If533cf7c4c379be78f5a15073accaff7f65973ab
    Closes-Bug: #1563070
    (cherry picked from 8382ac3717cf646145379456af94ce75000349a9)