This seems to be working now. Closing.
```console
$ guix describe -f channels-sans-intro
(list (channel
(name 'guix)
(url "https://git.guix.gnu.org/guix.git";)
(branch "master")
(commit
"e5e2aaaf558033f46eabe3717add9fb6a79042a8")))
$ guix build --debug=1 --file=test.scm
$ guix gc -D /gnu/store/*-hello-*
$ guix build --debug=1 --file=test.scm --no-substitutes
```Thanks, Owen
