Description of problem:
Scale up master failed due to undefined variable error.

Version-Release number of selected component (if applicable):
openshift-ansible-3.6.122-1.git.0.62fcd88.el7

How reproducible:
100%

Steps to Reproduce:
1. Prepare a HA env
2. Scaleup master
3. 

Actual results:
# ansible-playbook -i inventory -v /usr/share/ansible/openshift-ansible/playbooks/byo/openshift-master/scaleup.yml
...
TASK [openshift_master : set_fact] *********************************************
fatal: [host-8-175-47.host.centralci.eng.rdu2.redhat.com]: FAILED! => {
    "failed": true
}

MSG:

the field 'args' has an invalid value, which appears to include a variable that is undefined. The error was: {{ hostvars[groups.oo_first_master.0].l_clean_install }}: 'dict object' has no attribute 'l_clean_install'

The error appears to have been in '/usr/share/ansible/openshift-ansible/roles/openshift_master/tasks/main.yml': line 131, column 3, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:


- set_fact:
  ^ here
...

Expected results:
Scale up succeed.

Additional info: