isolate bi-directionally
isolate bi-directionally

without this, each other node would see mt4 disappear,
but mt4 would still get incoming messages from the others
(but refute them) and despite ping timeouts, it would keep
the others in its list

note that is is not perfect either. the propagation is slower than
expected, so will need to change the test to take longer or
switch memberlist to loopback config to converge faster

for i in 0 1 2 3 4 5; do echo dockerchaos_metrictank${i}_1; docker logs
dockerchaos_metrictank${i}_1 2>&1 | grep left | grep cluster; done
dockerchaos_metrictank0_1
2017/11/23 01:39:04 [I] CLU manager: Node metrictank4 has left the cluster
dockerchaos_metrictank1_1
2017/11/23 01:39:04 [I] CLU manager: Node metrictank4 has left the cluster
dockerchaos_metrictank2_1
2017/11/23 01:39:05 [I] CLU manager: Node metrictank4 has left the cluster
dockerchaos_metrictank3_1
2017/11/23 01:39:05 [I] CLU manager: Node metrictank4 has left the cluster
dockerchaos_metrictank4_1
2017/11/23 01:39:29 [I] CLU manager: Node metrictank2 has left the cluster
2017/11/23 01:39:36 [I] CLU manager: Node metrictank3 has left the cluster
2017/11/23 01:39:39 [I] CLU manager: Node metrictank0 has left the cluster
dockerchaos_metrictank5_1
2017/11/23 01:39:05 [I] CLU manager: Node metrictank4 has left the cluster

raintank/raintank-metric,raintank/metrictank,raintank/raintank-metric,raintank/metrictank,raintank/metrictank,replay/metrictank,replay/metrictank,replay/metrictank,raintank/raintank-metric,replay/metrictank,raintank/metrictank