Description of problem:
-----------------------
Attempt to setup heat config output without specifying container-registry-file failed:
(undercloud) [stack@undercloud-0 ~ (undercloud-12-us7)]$ openstack overcloud update stack --init-minor-update
You need to provide your container registry file if you want to update your container. If not, the old registry will be used for the minor update.
Started Mistral Workflow tripleo.package_update.v1.package_update_plan. Execution ID: 23c9c40b-9c3e-4263-b344-fe8d4a7f3931
Waiting for messages on queue '3e6535a4-a4cc-4f51-8fa1-9c099023117f' with no timeout.
{u'execution': {u'created_at': u'2017-10-02 14:03:29',
                u'id': u'23c9c40b-9c3e-4263-b344-fe8d4a7f3931',
                u'input': {u'config_dir': u'/tmp/',
                           u'container': u'overcloud',
                           u'container_registry': None,
                           u'queue_name': u'3e6535a4-a4cc-4f51-8fa1-9c099023117f',
                           u'skip_deploy_identifier': False,
                           u'timeout': 240},
                u'name': u'tripleo.package_update.v1.package_update_plan',
                u'params': {u'namespace': u''},
                u'spec': {u'description': u'Take a container and perform a package update with possible breakpoints',
                          u'input': [u'container',
                                     u'container_registry',
                                     {u'timeout': 240},
                                     {u'queue_name': u'tripleo'},
                                     {u'skip_deploy_identifier': False},
                                     {u'config_dir': u'/tmp/'}],
                          u'name': u'package_update_plan',
                          u'tags': [u'tripleo-common-managed'],
                          u'tasks': {u'get_config': {u'action': u'tripleo.config.get_overcloud_config',
                                                     u'name': u'get_config',
                                                     u'on-error': u'set_update_failed',
                                                     u'on-success': u'send_message',
                                                     u'type': u'direct',
                                                     u'version': u'2.0'},
                                     u'send_message': {u'action': u'zaqar.queue_post',
                                                       u'input': {u'messages': {u'body': {u'payload': {u'execution': u'<% execution() %>',
                                                                                                       u'message': u"<% $.get('message', '') %>",
                                                                                                       u'status': u"<% $.get('status', 'SUCCESS') %>"},
                                                                                          u'type': u'tripleo.package_update.v1.package_update_plan'}},
                                                                  u'queue_name': u'<% $.queue_name %>'},
                                                       u'name': u'send_message',
                                                       u'on-success': [{u'fail': u'<% $.get(\'get_config\') = "FAILED" %>'}],
                                                       u'type': u'direct',
                                                       u'version': u'2.0'},
                                     u'set_update_failed': {u'name': u'set_update_failed',
                                                            u'on-success': u'send_message',
                                                            u'publish': {u'message': u'<% task(update).result %>',
                                                                         u'status': u'FAILED'},
                                                            u'type': u'direct',
                                                            u'version': u'2.0'},
                                     u'update': {u'action': u'tripleo.package_update.update_stack container=<% $.container %> timeout=<% $.timeout %> container_registry=<% $.container_registry %>',
                                                 u'input': {u'container': u'<% $.container %>',
                                                            u'container_registry': u'<% $.container_registry %>',
                                                            u'timeout': u'<% $.timeout %>'},
                                                 u'name': u'update',
                                                 u'on-error': u'set_update_failed',
                                                 u'on-success': u'get_config',
                                                 u'type': u'direct',
                                                 u'version': u'2.0'},
                                     u'update_plan': {u'action': u'tripleo.plan.update_from_dir',
                                                      u'input': {u'container': u'<% $.container %>'},
                                                      u'name': u'update_plan',
                                                      u'on-error': u'set_update_failed',
                                                      u'on-success': u'update',
                                                      u'type': u'direct',
                                                      u'version': u'2.0'}},
                          u'version': u'2.0'}},
 u'message': u"Failed to run action [action_ex_id=fdc704cd-1b68-4893-bd79-4d21466437cb, action_cls='<class 'mistral.actions.action_factory.UpdateStackAction'>', attributes='{}', params='{u'container': u'overclou
d', u'timeout': 240, u'container_registry': None}']\n 'NoneType' object has no attribute '__getitem__'",
 u'status': u'FAILED'}

Version-Release number of selected component (if applicable):
-------------------------------------------------------------
python-tripleoclient-7.3.1-0.20170925220840.f114a61.el7ost.noarch

python-mistralclient-3.1.3-0.20170915002443.c33d39c.el7ost.noarch
openstack-mistral-api-5.1.1-0.20170925134000.d1a917e.el7ost.noarch
puppet-mistral-11.3.1-0.20170825184651.cf2e493.el7ost.noarch
openstack-mistral-executor-5.1.1-0.20170925134000.d1a917e.el7ost.noarch
openstack-mistral-common-5.1.1-0.20170925134000.d1a917e.el7ost.noarch
python-mistral-lib-0.2.0-0.20170821165722.bb1b87b.el7ost.noarch
openstack-mistral-engine-5.1.1-0.20170925134000.d1a917e.el7ost.noarch
python-mistral-5.1.1-0.20170925134000.d1a917e.el7ost.noarch

openstack-tripleo-common-7.6.1-0.20170922213744.el7ost.noarch
openstack-tripleo-common-containers-7.6.1-0.20170922213744.el7ost.noarch

Steps to Reproduce:
1. Install RHOS-12
2. Setup latest repos (UC and OC)
3. Apply patches: 487496, 487488, 486567
4. Update UC
5. Try setup heat config output:
    openstack overcloud update stack --init-minor-update

Actual results:
---------------
Error while setting up config output.