resize an instance should not set state to error if no host found

[jichenjc]

In resize operation there is code looks like:

if not instance['host']:
    self._set_instance_error_state(context, instance['uuid'])
    msg = _('Instance has no source host')
    raise exception.MigrationError(msg)

same_host = instance['host'] == self.host
if same_host and not CONF.allow_resize_to_same_host:
    self._set_instance_error_state(context, instance['uuid'])
    msg = _('destination same as source!')
    raise exception.MigrationError(msg)

however, it's not reasonable to set an instance to ERROR state if we can't find a host when we try to resize an instance
we'd better keep the instance in ACTIVE state and report there is no host

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/78897

[Tracy Jones (tjones-i)]

this has not been touched in a long time and the patches are abandoned. Please set back to in progress if you start to work on it

[jichenjc (jichenjc)]

due to remove comments, abandon