Comment 9 for bug 1790204

Why don't we just change the whole resize logic to always try resizing to the same host first (without ever touching the scheduler) and then only call the scheduler if the resize-on-same-host failed?

That way, we try the easy route first -- without ever touching allocation candidates or any of that mess, and we simply update the host's allocations for that instance using PUT /allocations/{instance_uuid}. That will return a 409 Conflict if the results of that updated allocation would exceed the provider's inventory (accounting for allocation ratios) and therefore we wouldn't need to involve the scheduler at all for same-host resizes.