Description of problem:
In certain cases CNS installation can fail when openshift_storage_glusterfs_wipe variable is set.

Version-Release number of selected component (if applicable):
[cloud-user@ansible-host openshift-ansible]$ git describe
openshift-ansible-3.7.14-1-2-g9349b3b

How reproducible:
Always on an openstack system provisioned by openshift-ansible-contrib.

Steps to Reproduce:
1. Install a openshift on OpenStack with openshift-ansible-contrib and set openshift_storage_glusterfs_wipe=true

TASK [openshift_storage_glusterfs : Unlabel any existing GlusterFS nodes] *********************************************************************************************************************
task path: /home/cloud-user/openshift-ansible/roles/openshift_storage_glusterfs/tasks/glusterfs_deploy.yml:19
fatal: [master-1.scale-ci.example.com]: FAILED! => {"failed": true, "msg": "the field 'args' has an invalid value, which appears to include a variable that is undefined. The error was: 'dict object' has no attribute 'openshift'\n\nThe error appears to have been in '/home/cloud-user/openshift-ansible/roles/openshift_storage_glusterfs/tasks/glusterfs_deploy.yml': line 19, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n- name: Unlabel any existing GlusterFS nodes\n  ^ here\n"}
ok: [master-1.scale-ci.example.com] => (item=lb-0.scale-ci.example.com) => {"changed": false, "item": "lb-0.scale-ci.example.com", "state": "absent"}
        to retry, use: --limit @/home/cloud-user/openshift-ansible/playbooks/byo/openshift-glusterfs/config.retry

Expected results:
Successful instalation.

Additional info:
The issue seems to be a missing check in "roles/openshift_storage_glusterfs/tasks/glusterfs_deploy.yml"

when: glusterfs_wipe

should be changed to

when: "'openshift' in hostvars[item] and glusterfs_wipe"

Fix tested and works fine.  Will create a PR that fixes this.