* guix/packages.scm (package-full-name): By default, use "@" to separate
the package name and package version. Add an optional delimiter
argument so that there is still a way to explicitly use a different
delimiter.
* gnu/packages/commencement.scm (gcc-boot0) <unpack-gmp&co>: Adjust
accordingly.
* tests/graph.scm: Adjust accordingly.
* tests/profiles.scm: Adjust accordingly.
* NEWS: Mention the change.
Fixes: <https://bugs.gnu.org/31088>.
Reported by Pierre Neidhardt <ambrevar@gmail.com>.
