copying logs from nodes doesn't work

[yuanying]

`_get_nodes_from_stack` will be never called because `_get_nodes_from_bay`
always return un-empty list if master_addresses and node_addresses are
None. So we can't get logs unless bay is succeeded to create.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/345197

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/345197
Committed: https://git.openstack.org/cgit/openstack/magnum/commit/?id=7963f205ce2ff9184c60a313633b99b4cd13194b
Submitter: Jenkins
Branch: master

commit 7963f205ce2ff9184c60a313633b99b4cd13194b
Author: OTSUKA, Yuanying <email address hidden>
Date: Thu Jul 21 16:01:21 2016 +0900

    Fix copying logs from nodes

    `_get_nodes_from_stack` will be never called because `_get_nodes_from_bay`
    always return un-empty list if master_addresses and node_addresses are
    None. So we can't get logs unless bay is succeeded to create.
    This patch fixes this issue, so we can get node logs if bay is not create
    completed.

    Change-Id: I6e518359d08cf06e95adc0b324c934c8f3e0c27d
    Closes-Bug: #1605092

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/magnum 3.0.0 release.