Comment 0 for bug 1270675

When one VM was shelve-offloaded, the VM won't belong to any hosts.
And the 'host' attribute will be 'None' if you execute 'nova show $id'. That's correct.

But 'unshelve' doesn't record 'host' attributes even if the instance has already spawned in one host.
Therefore, if you operate it later, the nova-api will raise an exception because it can't find the VM's host.

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