There is an issue with the default YAML loader, which allows arbitrary
code execution, as documented here:
https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation.
This can be avoided by using yaml.safe_load. We don't require Python
object serialisation, so safe_load is sufficient.
Change-Id: I09190766066ab56d04b1317a4022782160d60528
Story: 2005253
Task: 30050