1. start m1,m2,m3 with v3.4.0 binary
2. stop m2
3. restart m2 with 3.5.0-pre binary
4. etcdctl endpoint health --endpoints=localhost:2379,localhost:22379,localhost:32379
5. restart m3 with 3.5.0-pre binary
6. etcdctl endpoint health --endpoints=localhost:2379,localhost:22379,localhost:32379