Feature: cluster id mismatch check

tarantool> box.func['.raft_join']:call({"wrong-cluster-id", "i2", nil, "", true})
---
- error: 'cannot join the instance to the cluster: cluster_id mismatch: cluster_id
    of the instance = "wrong-cluster-id", cluster_id of the cluster = "c"'
...

Close #86 (closed)