Specify YAML loader
registrar gives:
/usr/bin/gwrucio_registrar:247: YAMLLoadWarning: calling yaml.load() without Loader=... is deprecated, as the default Loader is unsafe. Please read https://msg.pyyaml.org/load for full details.
rset = yaml.load(stream)
Fixes detailed in: https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation