Comment 1 for bug 1728722

We basically want something like this in the migration code that's swapping the allocations:

https://github.com/openstack/nova/blob/965f56d7d2ca1f668f70d24d4dcc20e418bb5b9c/nova/scheduler/client/report.py#L1013

Or we could implement this TODO in the placement server code, but that would require a microversion so the client can know if it's there or not and rely on the retry in the server, or if the client has to perform the retries:

https://github.com/openstack/nova/blob/965f56d7d2ca1f668f70d24d4dcc20e418bb5b9c/nova/objects/resource_provider.py#L1887