Regression - Cache-control header (pipe) not sets

[dmalki]

Describe the bug

• Node.js version: v15.2.1
• OS & version: macOS catalina 10.15.6

Pipe cache-Control header response is not sets in the latest got version, as it used to be in got version 10.7.0

Actual behavior

Cache-Control is not sets as it used to be in got version 10.7.0
...

Expected behavior

Cache-Control" header = "public, max-age=123456"
...

Code to reproduce

const got = require('got');
const chai = require('chai'), expect = chai.expect;

const client = got.extend({
throwHttpErrors: false,
timeout:20000,
retry:2
});
const express = require('express');
const app = express();
function fn(){
const readStream = client.stream('https://www.youtube.com/watch?v=RimGVSA_38o');
return readStream;
}

app.get('/', async (req, res) => {
const readStream = fn(req, res);
readStream.on("response", ()=> {
res.setHeader("Cache-Control", "public, max-age=123456");
}).on('error', (err) => {
console.log('Error in read stream...', err);
});

readStream.pipe(res);

});
app.listen(3000);

got('http://localhost:3000').then(response => {
expect(response.headers["cache-control"]).to.equal("public, max-age=123456");
console.log('Succedded');
}).catch(error => {
console.log(error.response);
});

...

{
"name": "AssertionError",
"message": "expected 'no-cache, no-store, max-age=0, must-revalidate' to equal 'public, max-age=123456'",
"showDiff": true,
"actual": "no-cache, no-store, max-age=0, must-revalidate",
"expected": "public, max-age=123456",
"stack": "AssertionError: expected 'no-cache, no-store, max-age=0, must-revalidate' to equal 'public, max-age=123456'\n at /Users/davidmalki/components/linear-jitp/got.js:29:50\n at processTicksAndRejections (node:internal/process/task_queues:93:5)"

}

Checklist

• [ X] I have read the documentation.
• [ X] I have tried my code with the latest version of Node.js and Got.

[szmarczak]

Please format the issue properly.

[dalebel]

I can't update the original issue, as I'm not the owner. But I'm pasting a simplified and edited version of the above code here, to reproduce the issue
Works with got got 10.7.0
Fails with got version 11.8.1
I run on node.js 14.15.0 on window 10.

const got = require('got');
const expect = require('chai').expect;
const express = require('express');
const app = express();

app.get('/', async (req, res) => {
    const readStream = got.stream('https://www.youtube.com/watch?v=RimGVSA_38o');
    readStream.on("response", ()=> {
        res.setHeader("Cache-Control", "public, max-age=123456");
    }).on('error', (err) => {
        console.log('Error in read stream...', err);
    });

    readStream.pipe(res);
});
app.listen(3000);

got('http://localhost:3000').then(response => {
    expect(response.headers["cache-control"]).to.equal("public, max-age=123456");
    console.log('Succedded');
});

[szmarczak]

This is not a regression. See szmarczak@d64298c

Got passes the headers it has received from the response after emitting the response event, so you can modify the response object. If you don't want to alter it, you need to listen for the end event instead.