“guix package -d” on empty profile downloads stuff

[Ricardo Wurmus <rekado@elephly.net>]

Hi Guix,

I have a little i686-linux laptop to which I deployed the Sugar desktop.
The only user account on that laptop (other than root) has no Guix
profile.

I switched to that user account and ran “guix package -d”.  Here is what
happened:

--8<---------------cut here---------------start------------->8---
$ guix package -d
substitute: updating substitutes from 'https://ci.guix.gnu.org'... 100.0%
25.8 MB will be downloaded
 glibc-2.35  8.5MiB                     1.0MiB/s 00:08 ▕██████████████████▏ 100.0%
 bash-minimal-5.1.16  603KiB            2.0MiB/s 00:00 ▕██████████████████▏ 100.0%
 gcc-11.3.0-lib  4.8MiB                 977KiB/s 00:05 ▕██████████████████▏ 100.0%
 libffi-3.4.4  57KiB                    588KiB/s 00:00 ▕██████████████████▏ 100.0%
 libunistring-1.0  671KiB               1.1MiB/s 00:01 ▕██████████████████▏ 100.0%
 pkg-config-0.29.2  218KiB              1.1MiB/s 00:00 ▕██████████████████▏ 100.0%
 libgc-8.2.2  219KiB                    767KiB/s 00:00 ▕██████████████████▏ 100.0%
 guile-3.0.9  8.1MiB                    1.3MiB/s 00:06 ▕██████████████████▏ 100.0%
 guile-3.0.9-debug  7.5MiB              1.4MiB/s 00:05 ▕██████████████████▏ 100.0%
substitute: updating substitutes from 'https://ci.guix.gnu.org'... 100.0%
0.4 MB will be downloaded
 glibc-utf8-locales-2.35  382KiB        266KiB/s 00:01 ▕██████████████████▏ 100.0%
guix package: error: profile '/var/guix/profiles/per-user/xxx/guix-profile' does not exist
--8<---------------cut here---------------end--------------->8---

Why do we need to download 25.8 MB to decide that we can’t do anything
here?

My usual excuse when faced with questions of this kind what always that
profile hooks may need to run, and they may require more recent versions
of tools to be built first.  Here we don’t seem to have a good reason
for that though.

-- 
Ricardo