config-download: Handle None value RoleConfig stack output

[James Slagle]

RoleConfig can exist as a stack output, but have a value of None. That case should be handled and set a default value of {} where the value was previously None.

Otherwise, the following traceback results when trying to use --config-download:

(undercloud) [stack@undercloud ~]$ tripleo-config-download
INFO:tripleo_common.utils.config.Config:Generating configuration under the directory: tripleo-config-download/tripleo-gDmruU-config
Traceback (most recent call last):
  File "/usr/bin/tripleo-config-download", line 56, in <module>
    stack_config.download_config(args.stack_name, args.output_dir)
  File "/usr/lib/python2.7/site-packages/tripleo_common/utils/config.py", line 194, in download_config
    for config_name, config in six.iteritems(role_config):
  File "/usr/lib/python2.7/site-packages/six.py", line 599, in iteritems
    return d.iteritems(**kw)
AttributeError: 'NoneType' object has no attribute 'iteritems'

The scenario where the value is None is when deploying where are roles have an empty set of services, such as when using environments/overcloud-baremetal.yaml with split-stack.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/542947

[James Slagle (james-slagle)]

https://review.openstack.org/542947

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/542947
Committed: https://git.openstack.org/cgit/openstack/tripleo-common/commit/?id=d384f4ecb63f578a6dd3468934c6b5086094b04e
Submitter: Zuul
Branch: master

commit d384f4ecb63f578a6dd3468934c6b5086094b04e
Author: James Slagle <email address hidden>
Date: Fri Feb 9 11:56:04 2018 -0500

    Handle None value for RoleConfig

    RoleConfig can exist as a stack output, but have a value of None. That
    case should be handled with a default value of {} where the value was
    previously None.

    Change-Id: I3caf31c00ab8c47d71a68eb82114fb398a47961b
    Closes-Bug: #1748482

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/tripleo-common 8.5.0 release.