postinstall output is not complete

[ooooevan]

Bug description

I use postinstall hook in my package,the output is not complete，maybe related to #5476.

When the postinstall runs right,there is no output ,when runs wrong, it will get the wrong output.
but my wrong output is not complete

 yarn add test-postinstall-o@1.1.0

The postinstall code is :

console.log('postinstall...');
console.log('postinstall...');
console.log('postinstall...');
console.log('will exit with code 1');
process.exit(1);

What is the current behavior?

The first time, in Windows PowerShell ,i got the full output:

postinstall...
postinstall...
postinstall...
will exit with code 1

After this time, i didn't get the complete output any more,

I delete node_modules and still like that

I was confused and i use the Git Bash,i always got the complete output

What is the expected behavior?

I should get the complete output like the first time,or where to clean the cache

Environment

• Node Version: 12.16.1
• Yarn v1 Version: 1.22.0
• OS and version: win 10

[ooooevan]

By the way, the reason i found this is that: i didn't got the output when the postinstall script get wrong,and i got the output when i use --verbose .

[shiftj18]

Has some config like npm foreground-scripts ?