'Unrescue the specified instance.
- unplug the instance VM\'s disk from the rescue VM.
- teardown the rescue VM.
- release the bootlock to allow the instance VM to start.'

def unrescue(self, instance):

    rescue_vm_ref = vm_utils.lookup(self._session, ('%s-rescue' % instance.name))
    if (not rescue_vm_ref):
        raise exception.InstanceNotInRescueMode(instance_id=instance.uuid)
    original_vm_ref = self._get_vm_opaque_ref(instance)
    self._destroy_rescue_instance(rescue_vm_ref, original_vm_ref)
    self._release_bootlock(original_vm_ref)
    self._start(instance, original_vm_ref)
