Bug Description

Given a query string consisting of just a question mark (but no actual parameters), Undici fetch drops the query string entirely, while browser fetch does not.

Reproducible By

fetch("https://testserver.host/echo?").then(async (r) => console.log(await r.text()))

If you go to https://testserver.host/ and run this in the console, using browser native fetch, you'll see:

GET /echo? HTTP/1.1
Host: testserver.host
...

If you run it with Undici fetch, you'll see:

GET /echo HTTP/1.1
host: testserver.host
...

Expected Behavior

The question mark should be preserved. It's part of the URL, it's perfectly valid, servers can interpret it differently to a query string if they want to, it's what everybody will expect, and we should match fetch behaviour if possible.

Environment

Confirmed with latest Firefox & Chrome vs Undici v7.22.0

Additional context

I suspect this is because WHATWG URL has this same behaviour when parsing URLs for both fragments & query strings, and we're using this to extract the query string. We'll need to check that more carefully. Node-fetch had the same problem, fixed here: node-fetch/node-fetch#782

There is discussion in WHATWG about this as a general problem in URL parsing, see whatwg/url#779 for more info.

I'm happy to work on this, I'll take a look sometime this week but let me know if there's any objections or somebody else working on this or similar.