Comment 8 for bug 1834094

in order to pass through that last issue, I had to:
- config download
- edit deploy_steps_playbook.yaml
- add a new condition for the following tasks:
° NetworkConfig stdout
° Write rc of NetworkConfig script
The condition was: NetworkConfig_result is changed

Doing so, in addition to James' patch + my proposal (create empty file nonetheless) allowed me to get a successful overcloud deploy.