Description of problem:
Upgrade ocp cluster from v3.6 to v3.7, upgrade failed for an undefined variable oreg_auth_credentials_replace.

Failure summary:


  1. Hosts:     x.x.x.x
     Play:     Upgrade master
     Task:     Create credentials for registry auth
     Message:  The conditional check '(not master_oreg_auth_credentials_stat.stat.exists or oreg_auth_credentials_replace) | bool' failed. The error was: error while evaluating conditional ((not master_oreg_auth_credentials_stat.stat.exists or oreg_auth_credentials_replace) | bool): 'oreg_auth_credentials_replace' is undefined
               
               The error appears to have been in '/usr/share/ansible/openshift-ansible/roles/openshift_master/tasks/registry_auth.yml': line 8, column 3, but may
               be elsewhere in the file depending on the exact syntax problem.
               
               The offending line appears to be:
               
               
               - name: Create credentials for registry auth
                 ^ here


Add "oreg_auth_credentials_replace=false" in inventory file can workaround.

Version-Release number of the following components:
openshift-ansible-3.7.0-0.158.0.git.0.8941dd5.el7.noarch

How reproducible:
always

Steps to Reproduce:
1. Upgrade v3.6 to v3.7
2.
3.

Actual results:
Upgrade failed.

Expected results:
Upgrade succeed.

Additional info:
Inventory file and log in attachment.