Comment 7 for bug 1701061

Right you are, now that is what you get for not quoting the whole context of the log output:
DEBUG:runner:2017-06-16 23:48:29,193 get_unit_hostnames DEBUG: Unit host names: {'rabbitmq-server/6': 'juju-4d268d-auto-osci-sv06-15', 'rabbitmq-server/7': 'juju-4d268d-auto-osci-sv06-16'}
DEBUG:runner:2017-06-16 23:48:34,445 run_cmd_unit DEBUG: rabbitmq-server/6 `rabbitmqctl cluster_status` command returned 0 (OK)
DEBUG:runner:2017-06-16 23:48:34,446 get_rmq_cluster_status DEBUG: rabbitmq-server/6 cluster_status:
DEBUG:runner:Cluster status of node 'rabbit@juju-4d268d-auto-osci-sv06-15' ...
DEBUG:runner:[{nodes,[{disc,['rabbit@juju-4d268d-auto-osci-sv06-15',
DEBUG:runner: 'rabbit@juju-4d268d-auto-osci-sv06-16',
DEBUG:runner: 'rabbit@juju-4d268d-auto-osci-sv06-17']}]},
DEBUG:runner: {running_nodes,['rabbit@juju-4d268d-auto-osci-sv06-16',
DEBUG:runner: 'rabbit@juju-4d268d-auto-osci-sv06-17',
DEBUG:runner: 'rabbit@juju-4d268d-auto-osci-sv06-15']},
DEBUG:runner: {cluster_name,<<"rabbit@juju-4d268d-auto-osci-sv06-17">>},
DEBUG:runner: {partitions,[]}]
DEBUG:runner:2017-06-16 23:48:39,713 run_cmd_unit DEBUG: rabbitmq-server/7 `rabbitmqctl cluster_status` command returned 0 (OK)
DEBUG:runner:2017-06-16 23:48:39,713 get_rmq_cluster_status DEBUG: rabbitmq-server/7 cluster_status:
DEBUG:runner:Cluster status of node 'rabbit@juju-4d268d-auto-osci-sv06-16' ...
DEBUG:runner:[{nodes,[{disc,['rabbit@juju-4d268d-auto-osci-sv06-15',
DEBUG:runner: 'rabbit@juju-4d268d-auto-osci-sv06-16']}]},
DEBUG:runner: {running_nodes,['rabbit@juju-4d268d-auto-osci-sv06-15',
DEBUG:runner: 'rabbit@juju-4d268d-auto-osci-sv06-16']},
DEBUG:runner: {cluster_name,<<"rabbit@juju-4d268d-auto-osci-sv06-17">>},
DEBUG:runner: {partitions,[]}]
DEBUG:runner:['Cluster registration check failed on rabbitmq-server/6: rabbit@juju-4d268d-auto-osci-sv06-17 should not be registered with RabbitMQ after unit removal.\n']
DEBUG:runner:Exit Code: 1