Concurrency issue when using yarn in script

[scherler]

I am running into the following issue:

If you run yarn in a script like

"scripts": {
   "3": "yarn 1 && yarn 2"
}

you get on my system running yarn 3: warning Waiting for the other yarn instance to finish (17783) and to go on I need to kill the process by hand.

◎ uname -a
Linux mysterion 4.18.0-2-amd64 #1 SMP Debian 4.18.10-2 (2018-11-02) x86_64 GNU/Linux
◎ yarn -v
1.12.3
◎ which yarn
/home/mysterion/.yarn/bin/yarn
◎ node -v              
v8.11.2

However I tested a couple of yarn version the problem exist in any of them.

I created a small demo project to help testing https://github.com/scherler/yarnWhitinYarn

What is the current behavior?

Yarn is waiting for the other yarn instance to finish.

What is the expected behavior?
Yarn should not has to be killed by hand.

[reaktivo]

Seems to be related to #6650, which is still causing some issues for us

[scherler]

thanks will try another version