Overcloud deploy fails on ffwd upgrading ceph when mgr isn't defined

Issue

• Notice "Please add a mgr host to your inventory"

openstack workflow execution show 2990f1c0-0a98-4714-9ce9-aac3223da7f7
|                    |  Unexpected error while running command.              
|                    | Command: ansible-playbook /usr/share/ceph-ansible/infrastructure-playbooks/rolling_update.yml --user tripleo-admin --become --become-user root --extra-vars {"ireallymeanit": "yes"} --inventory-file /tmp/ansible-mistral-actionhhFsQc/inventory.yaml --private-key /tmp/ansible-mistral-actionhhFsQc/ssh_private_key --skip*** package-install,with_pkg       
|                    | Exit code: 2   
|                    | Stdout: u'\nPLAY [confirm whether user really meant to upgrade the cluster] ****************\n\nTASK [Gathering Facts] *********************************************************\nThursday 17 January 2019  15:28:59 -0200 (0:00:00.090)       0:00:00.090 ****** \nok: [localhost]\n\nTASK [exit playbook, if user did not mean to upgrade cluster] ******************\nThursday 17 January 2019  15:29:02 -0200 (0:00:02.309)       0:00:02.400 ****** \nskipping: [localhost]\n\nTASK [fail if no mgr host is present in the inventory] *************************\nThursday 17 January 2019  15:29:02 -0200 (0:00:00.064)       0:00:02.465 ****** \nfatal: [localhost]: FAILED! => {"changed": false, "failed": true, "msg": "Please add a mgr host to your inventory."}\n\nPLAY RECAP *********************************************************************\nlocalhost                  : ok=1    changed=0    unreachable=0    failed=1   \n\n\nThursday 17 January 2019  15:29:02 -0200 (0:00:00.076)       0:00:02.541 ****** \n=============================================================================== \n'

• Output from failed deploy command

2019-01-17 17:29:09Z [overcloud]: UPDATE_FAILED  Resource UPDATE failed: resources.AllNodesDeploySteps: Resource UPDATE failed: resources.WorkflowTasks_Step2_Execution: ERROR<br data-hasqtip="true"><br data-hasqtip="true"> Stack overcloud UPDATE_FAILED <br data-hasqtip="true"><br data-hasqtip="true">overcloud.AllNodesDeploySteps.WorkflowTasks_Step2_Execution:<br data-hasqtip="true">  resource_type: OS::TripleO::WorkflowSteps<br data-hasqtip="true">  physical_resource_id: 2990f1c0-0a98-4714-9ce9-aac3223da7f7<br data-hasqtip="true">  status: UPDATE_FAILED<br data-hasqtip="true">  status_reason: |<br data-hasqtip="true">    resources.WorkflowTasks_Step2_Execution: ERROR<br data-hasqtip="true">Heat Stack update failed.<br data-hasqtip="true">Heat Stack update failed.