fetch() keeps the original URL after redirects #5310

fetch() follows redirects, but the resulting Response still reports the original URL and redirected === false.

Repro against a local server that returns 302 Location: /target#frag:

const r = await fetch("http://127.0.0.1:8131/redirect");
console.log(r.redirected, r.url);

Current Boa:

• false
• http://127.0.0.1:8131/redirect

Expected:

• true
• http://127.0.0.1:8131/target

This matches Node and the Fetch spec for Response.redirected and Response.url.