Authentication of newly added Registries takes place on the main Rack. On a public Rack, the source IP address cannot be verified. If the Registry is IP-locked for security, the
PrivateBuild Rack parameter should be used to ensure a known IP address for the Build Instance. Racks with
PrivateBuild=Yes will now no longer authenticate against a registry when it is added. If invalid credentials are provided in this case, this will not surface until a build is attempted, at which point the registry can be removed and re-added with correct credentials.