Don't change pyyaml behavior
Don't change pyyaml behavior

When an application load heatclient, the default pyyaml behavior change.

This ensures only heatclient use it's custom pyyaml stuffs.

This currently breaks the telemetry gate if the tempest heat plugin is
loaded with the telemetry.

Change-Id: I5d7d1a1999e762f2285a0effc081252570f24de8

openstack/python-heatclient