问题描述：目前使用tidb版本4.0-rc。是由tidb3.0.4升级上来的（使用ansiable升级的），tiup单独进行安装的。现在想在原有tidb集群的基础上扩容tiflash节点，运行扩容命令出现如下错误：
tidb>$ tiup cluster scale-out test-cluster scale-out.yaml Starting component
cluster: /home/tidb/.tiup/components/cluster/v0.6.0/cluster scale-out test-cluster scale-out.yaml
Error: cannot scale-out non-exists cluster test-cluster
Verbose debug logs has been written to /home/tidb/tidb-ansible/logs/tiup-cluster-debug-2020-05-18-14-52-33.log. Error: run
/home/tidb/.tiup/components/cluster/v0.6.0/cluster(wd:/home/tidb/.tiup/data/RzJuoBY) failed: exit status 1
