Description of problem:
[This is just a clone of an upstream BZ]
https://bugs.launchpad.net/nova/+bug/1417667
Currently in OSP7, this is not present, hence migrating
(live/cold) fails if there are other instances using
the same cpu-range on the destination compute node.
As a result, the instance can only be started after
making sure the existing/running instance stop using
the vcpu(and hence the pcpus its assigned to).