Why is the Ansible Tower Installation Failing at Task "packages_el : Install postgres with error: Task object has no attribute async_val"?

문제

Tower setup is failing at the below task:

TASK [packages_el : Install postgres] *************************************************************************************************
An exception occurred during task execution. To see the full traceback, use -vvv. The error was: AttributeError: 'Task' object has no attribute 'async_val'
fatal: [localhost]: FAILED! => {"failed": true, "msg": "Unexpected failure during module execution.", "stdout": ""}
    to retry, use: --limit @/root/ansible-tower-setup-3.4.0-2/install.retry

PLAY RECAP ****************************************************************************************************************************
localhost                  : ok=34   changed=7    unreachable=0    failed=1