refer to https://review.openstack.org/#/c/399354/ Change-Id: If33e4ad7358136b88965679a9877e87487f812ea Partially-implements: blueprint condition-pre-check
* Merge prechecks.yml and site.yml playbook * Create empty precheck.yml into all roles. Change-Id: I8a138558a26c0a2a66c5fd48ed37be657c99c1dd Implements: blueprint condition-pre-check