`cookie` no longer able to be set in the Headers API as of v5.2.0

Bug Description

Upgrading Node from 18.1 to 18.2 we are no longer able to set the cookie header in the Headers API.

Seems this is a result of https://github.com/nodejs/undici/pull/1337

Reproducible By

const headers = new Headers();
headers.append('cookie', 'bar=baz; foo=bar');

fetch('https://httpbin.org/cookies', {
  headers,
})
  .then(res => res.json())
  .then(console.log);

Running the above code on Node 18.1:

{ cookies: { bar: 'baz', foo: 'bar' } }

On Node 18.2 (and undidi 5.2):

{ cookies: {} }

Curiously if I don’t use the Headers API and set the cookie header directly it works:

fetch('https://httpbin.org/cookies', {
  headers: {
    cookie: 'bar=baz; foo=bar',
  },
})
  .then(res => res.json())
  .then(console.log);

// { cookies: { bar: 'baz', foo: 'bar' } }

Expected Behavior

Would expect to be able to still set the cookie header because we can’t use document.cookie like you can use in browser environments.

Environment

• OSX 11.6
• Node 18.1 and Node 18.2 using nvm

[benjamingr]

Hey, @issuefiler.

Node landed an experimental implementation of fetch given some semantics people think make sense. Part of the fact it’s experimental is because we are explicitly looking for feedback and to see how people think fetch should behave.

Please be mindful of how you phrase yourself. Your comment comes off (to me) as harsh whereas this sort of feedback (the technical bits) are welcome. There are many people using Node.js with different requirements, preferences and ideas about what APIs should do and Node.js is happy to listen to those users in good faith and reconsider API choices.

Your comment makes this a bit hard given the tone. If you want effective discourse I recommend you consider a different approach/tone towards the volunteers working on new features for the platform.

[KhafraDev]

That section of the code deals with setting cookies in a per-origin browser cookie jar, not getting/setting/sending set-cookie headers. See #1262