The test_templates_negative haves heat to connect to an external service. www.example.com is a registered existing domain, and it also has an AAAA record. But if you do not have external ipv6 connectivity the test fails after a long time. Tempest should not depends on the example.org behavior.
The issue was resolved in the new version of openstack-tempest-liberty package. Tested by an internal Jenkins jobs with director_puddle: 2018-06-05.1.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2018:2133