Since PyYAML 5.1, yaml.load without specifying the Loader option is
deprecated and shows the following warning.
YAMLLoadWarning: calling yaml.load() without Loader=... is deprecated,
as the default Loader is unsafe.
Please read https://msg.pyyaml.org/load for full details.
This change replaces usage of yaml.load by yaml.safe_load, to get rid
of that warning message.
Change-Id: Ibe25c4aaf3aa7226f28ec60b8a929ecc143face1
f83108d858