LOG a warning if the heartbeat can not be validated
LOG a warning if the heartbeat can not be validated

If for some reason the heartbeat can not occur instead
of failing silently it is better to at least log a message
so that operators can investigate the underlying issue.

Change-Id: Ide88314c413afa389d6c039478324d6e47f63e82

citrix-openstack-build/tooz,openstack/tooz,citrix-openstack-build/tooz,openstack/tooz