Playground incorrectly detected that tidb failed to start

[unbyte]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

tiup playground --host 0.0.0.0 --tiflash 1

2. What did you expect to see?

outputs

To connect TiDB: mysql --host %s --port %s -u root

and start tiflash

3. What did you see instead?

tidb start successfully but outputs

Playground Bootstrapping...
Start pd instance
Start tikv instance
Start tidb instance
Waiting for tidb localhost:4000 ready  ... Error
To view the dashboard: http://localhost:2379/dashboard
To view the Prometheus: http://0.0.0.0:9090
To view the Grafana: http://0.0.0.0:3000

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

v1.2.0 tiup
Go Version: go1.13
Git Branch: bump
GitHash: 7e35be8

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I use tiup in Ubuntu 18 for WSL. And this happens occasionally.

[unbyte]

It's due to that in my host tidb can't be connected until after 60 attempts to connect. can provide any way to set a custom max wait time for starting tidb?