`stripHopByHop` copies headers with `out.set(key, value)`, which overwrites.
Correct for every header except the one that legitimately repeats: a NextAuth
sign-in sends several Set-Cookie - csrf-token, callback-url, session-token - and
collapsing them to one drops the rest.
Measured: two Set-Cookie headers direct from Linkwarden, one through the door,
and the survivor was callback-url. So the csrf cookie never reached the browser,
the sign-in posted, failed its CSRF check and bounced back to the form. A
redirect loop with nothing in any log saying why - and the owner predicted this
exact symptom from the other side before it was found.
`getSetCookie()` returns them unjoined, which is the reason to use it rather than
splitting a combined value: `Expires` contains a comma, so naive splitting
corrupts the date and the cookie is discarded.
Both hops use this one function, so both are fixed by it.
pastilhas
f7c9a28c33