The fix for RHOS-8 came in via the recent rebase

    https://bugzilla.redhat.com/show_bug.cgi?id=1381466 --  rebase to 12.0.5

That's available via: openstack-nova-12.0.5-1.el7ost


I quickly verified it by:

-------------------------------------------------------------------------
$ rpm2cpio openstack-nova-12.0.5-1.el7ost.src.rpm | \
    cpio --extract --make-directories

$ tar -xzf nova-12.0.5.tar.gz 

Find the existence of the _release_floating_ip_and_refresh_cache() method, which came in via the commit[x]

$ grep _release_floating_ip_and_refresh_cache nova/network/neutronv2/api.py 
        def _release_floating_ip_and_refresh_cache(self, context, instance,
            _release_floating_ip_and_refresh_cache(self, context, instance,
-------------------------------------------------------------------------

[x] As verified on rhos/nova (rhos-8.0-patches) branch:
-----------------------------------------------------------------
$ git show 15cfd039fe30456e9ff19cfb9572d981c6b991f6  --stat
commit 15cfd039fe30456e9ff19cfb9572d981c6b991f6
Author: Michael Wurtz <michael.wurtz@ibm.com>
Date:   Thu Aug 18 14:53:33 2016 -0500

    Refresh info_cache after deleting floating IP
    
    When deleting a floating IP associated with Neutron's info_cache we don't
    refresh the info_cache after it is deleted.
    This patch makes it so the info_cache is refreshed when an associated
    floating IP is deleted. If there is no info_cache associated with the
    floating IP then info_cache is not refreshed.
    
    Change-Id: I8a8ae8cdbe2d9d77e7f1ae94ebdf6e4ad46eaf00
    Closes-Bug:  #1614538
    (cherry picked from commit cdb9b6820dc17971bca24adfc0b56f030f0ae827)
    (cherry picked from commit a832e6b2a019323fdf00e30302ad5c3c809baa21)

 nova/network/neutronv2/api.py             | 14 ++++++++++++--
 nova/tests/unit/network/test_neutronv2.py | 15 +++++++++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)
-----------------------------------------------------------------

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2016-2991.html