The source URI for 'trilios-serial-xyce' serves a 404 page.  Following
download links from the home page only leads to the git repository.

This package should probably be changed to download a tagged git
revision instad of attempting to fetch a defunct tarball.

ci.guix.gnu.org has a copy of the previous source tarball so it's not
very urgent (anyone coming here can add "--fallback" to their guix
invokation to get it).