Comment 3 for bug 1659215

This is not a bug, this is the expected behavior of the floating ip API in Neutron. Please look at this Tempest test case failure that was triggered by the proposed fix (https://review.openstack.org/#/c/425563/):

http://logs.openstack.org/63/425563/1/check/gate-tempest-dsvm-neutron-linuxbridge-ubuntu-xenial/4601f1d/console.html#_2017-01-26_08_51_05_811634

The source of this test is the following:

https://github.com/openstack/tempest/blob/master/tempest/api/network/test_floating_ips.py#L65

We are clearly saying in this test case's code that we allow to change a floating ip association without disassociating if before