Comment 3 for bug 1626955

> 2. Provide some way to merge in (e.g append, or redefine when role
> names collide) user provided roles with those defined by the default

Why do we need to merge role definitions if any issues/duplicates/collision in roles_data.yaml? Validate role definitions and stop the deploy should be the way, is what i feel. Please correct me if I am missing something.