If Request is passed as the first parameter and no header is passed, the set-cookie header is not cloned.

[tsctx]

Bug Description

If Request is passed as the first parameter and no header is passed, the set-cookie header is not cloned.

Reproducible By

const request = new Request("https://example.com", { headers: { "set-cookie": "A"  } });
const req = new Request(request);
req.headers.append("set-cookie", "B");
console.log(request.headers.getSetCookie()); //  [ 'A', 'B' ]
console.log(req.headers.getSetCookie()); // [ 'A', 'B' ]
console.log(request.headers.get("set-cookie")); // 'A'
console.log(req.headers.get("set-cookie")); // 'A, B'

Expected Behavior

const request = new Request("https://example.com", { headers: { "set-cookie": "A"  } });
const req = new Request(reqeust);
req.headers.append("set-cookie", "B");
console.log(request.headers.getSetCookie()); //  [ 'A' ]
console.log(req.headers.getSetCookie()); // [ 'A', 'B' ]
console.log(request.headers.get("set-cookie")); // 'A'
console.log(req.headers.get("set-cookie")); // 'A, B'

Logs & Screenshots

> $ node
Welcome to Node.js v21.1.0.
Type ".help" for more information.
> const request = new Request("https://example.com", { headers: { "set-cookie": "A"  } });
undefined
> const req = new Request(request);
undefined
> req.headers.append("set-cookie", "B");
undefined
> console.log(request.headers.getSetCookie());
[ 'A', 'B' ]
undefined
> console.log(req.headers.getSetCookie());
[ 'A', 'B' ]
undefined
> console.log(request.headers.get("set-cookie"))
A
undefined
> console.log(req.headers.get("set-cookie"))
A, B
undefined

Environment

Additional context