Writing xattr fails when protocol is guessed

[ilmari]

I did this

❯ curl --location --xattr -o curl.html curl.se
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100  8684  100  8684    0     0  78961      0 --:--:-- --:--:-- --:--:-- 78961
Warning: Error setting extended attributes on 'curl.html': Success

I expected the following

The user.xdg.origin.url xattr to be set to the URL including the guessed protocol, i.e. http://curl.se/.

curl/libcurl version

curl 8.5.0 (x86_64-pc-linux-gnu) libcurl/8.5.0 OpenSSL/3.0.13 zlib/1.2.13 brotli/1.0.9 zstd/1.5.4 libidn2/2.3.3 libpsl/0.21.2 (+libidn2/2.3.3) libssh2/1.10.0 nghttp2/1.52.0 librtmp/2.3 OpenLDAP/2.5.13
Release-Date: 2023-12-06, security patched: 8.5.0-2~bpo12+1
Protocols: dict file ftp ftps gopher gophers http https imap imaps ldap ldaps mqtt pop3 pop3s rtmp rtsp scp sftp smb smbs smtp smtps telnet tftp
Features: alt-svc AsynchDNS brotli GSS-API HSTS HTTP2 HTTPS-proxy IDN IPv6 Kerberos Largefile libz NTLM PSL SPNEGO SSL threadsafe TLS-SRP UnixSockets zstd

operating system

Linux ilmari-thinkpad 6.1.0-13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.55-1 (2023-09-29) x86_64 GNU/Linux

[ilmari]

looks like this was broken by #3433