Comment 11 for bug 1597596

This looks like a similar issue that we're seeing, and we're using the libvirt driver, which doesn't override deallocate_networks_on_reschedule.

In our scenario, we're seeing the instance get built with 2 or 3 fixed IPs instead of just the one. It seems that on retry a whole new port is allocated, even though there was already one allocated from the first attempt. Since our networks are more portable, they succeed in building with multiple ports, which is slightly different than what the proposed patch is trying to address.