TiUP doesn't download tiflash component in playground subcommand and reports 'queer' error message.

[iosmanthus]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

• tiup playground nightly or
• tiup playground nightly --pd 1 --db 1 --kv 1 --tiflash 1

However, this issue won't occur while I specify a version to these components.

2. What did you expect to see?

Create a local TiDB cluster normally.

3. What did you see instead?

🕙 14:30:57 ❯ tiup playground nightly
Starting component `playground`: /home/iosmanthus/.tiup/components/playground/v1.2.3/tiup-playground nightly
Playground Bootstrapping...
Start pd instance
Start tikv instance
Start tidb instance
Waiting for tidb 127.0.0.1:4000 ready  ... ⠏ 
Waiting for tidb 127.0.0.1:4000 ready  ... Done
Waiting for tikv 127.0.0.1:20160 ready  ... Done
Start tiflash instance
TiFlash failed to start: error requesting http://127.0.0.1:2379/pd/api/v1/config/replicate, response: "cannot update MaxReplicas when placement rules feature is enabled, please update rule instead"
, code 500
CLUSTER START SUCCESSFULLY, Enjoy it ^-^
To connect TiDB: mysql --host 127.0.0.1 --port 4000 -u root
To view the dashboard: http://127.0.0.1:2379/dashboard
To view the Prometheus: http://127.0.0.1:45943
To view the Grafana: http://127.0.0.1:3000

4. What version of TiUP are you using (tiup --version)?

v1.2.3 tiup
Go Version: go1.13
Git Branch: release-1.2
GitHash: df7e28a