Comment 4 for bug 1670627

So the instance gets put into the cell0 database and the _bury_in_cell0 method in conductor manager deletes the build request. Then when we delete the instance, the build request is gone but we find the instance via the instance mapping and know it's in cell0. The problem is we don't do any quota cleanup here:

https://github.com/openstack/nova/blob/master/nova/compute/api.py#L1799

Like we would have if we deleted the build request in the API (which is not the case for this bug):

https://github.com/openstack/nova/blob/master/nova/compute/api.py#L1729-L1756