Deployment with ceph fails with: "WorkflowTasks_Step2_Execution: ERROR"  "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'. Host key verification failed."


Environment:
openstack-puppet-modules-11.0.0-0.20170828113154.el7ost.noarch
instack-undercloud-7.4.2-0.20171010064304.el7ost.noarch
puppet-ceph-2.4.2-0.20170927195215.718a5ff.el7ost.noarch
ceph-ansible-3.0.3-1.el7cp.noarch
openstack-tripleo-heat-templates-7.0.3-0.20171014102841.el7ost.noarch


Steps to reproduce:
Attempt to deploy with:
openstack overcloud deploy --templates \
--libvirt-type kvm \
-e /home/stack/templates/nodes_data.yaml \
-e  /usr/share/openstack-tripleo-heat-templates/environments/ceph-ansible/ceph-ansible.yaml \
-e /usr/share/openstack-tripleo-heat-templates/environments/network-isolation.yaml \
-e /home/stack/virt/network/network-environment.yaml \
-e /usr/share/openstack-tripleo-heat-templates/environments/ssl/enable-tls.yaml \
-e /home/stack/virt/public_vip.yaml \
-e /usr/share/openstack-tripleo-heat-templates/environments/ssl/tls-endpoints-public-ip.yaml \
-e /home/stack/inject-trust-anchor-hiera.yaml \
-e /home/stack/rhos12.yaml


Result:
The deployment fails:
CREATE_IN_PROGRESS  state changed\n2017-10-20 00:52:12Z [overcloud.AllNodesDeploySteps.WorkflowTasks_Step2_Execution]: CREATE_FAILED  resources.WorkflowTasks_Step2_Execution: ERROR\n2017-10-20 00:52:13Z [overcloud.AllNodesDeploySteps]: CREATE_FAILED  Resource CREATE failed: resources.WorkflowTasks_Step2_Execution: ERROR\n2017-10-20 00:52:13Z [overcloud.AllNodesDeploySteps]: CREATE_FAILED  resources.AllNodesDeploySteps: Resource CREATE failed: resources.WorkflowTasks_Step2_Execution: ERROR\n2017-10-20 00:52:13Z [overcloud]: CREATE_FAILED  Resource CREATE failed: resources.AllNodesDeploySteps: Resource CREATE failed: resources.WorkflowTasks_Step2_Execution: ERROR\n\n Stack overcloud CREATE_FAILED \n\novercloud.AllNodesDeploySteps.WorkflowTasks_Step2_Execution:\n  resource_type: OS::Mistral::ExternalResource\n  physical_resource_id: 99c12b7f-ed4e-494b-9da3-f66c59ccce53\n  status: CREATE_FAILED\n  status_reason: |\n    resources.WorkflowTasks_Step2_Execution: ERROR"
 }


Digging through mistral logs I see:
onnect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}]}
2017-10-19 17:56:37,061 p=23479 u=mistral |  failed: [192.168.24.12] (item=192.168.24.22) => {"item": "192.168.24.22", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}
2017-10-19 17:56:37,113 p=23479 u=mistral |  failed: [192.168.24.12] (item=192.168.24.6) => {"item": "192.168.24.6", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}
2017-10-19 17:56:37,113 p=23479 u=mistral |  fatal: [192.168.24.12]: UNREACHABLE! => {"changed": false, "msg": "All items completed", "results": [{"_ansible_item_result": true, "item": "192.168.24.11", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}, {"_ansible_item_result": true, "item": "192.168.24.12", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}, {"_ansible_item_result": true, "item": "192.168.24.9", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}, {"_ansible_item_result": true, "item": "192.168.24.21", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}, {"_ansible_item_result": true, "item": "192.168.24.16", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}, {"_ansible_item_result": true, "item": "192.168.24.18", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}, {"_ansible_item_result": true, "item": "192.168.24.22", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}, {"_ansible_item_result": true, "item": "192.168.24.6", "msg": "Failed to connect to the host via ssh: Could not create directory '/home/mistral/.ssh'.\r\nHost key verification failed.\r\n", "unreachable": true}]}