bug#52943: Cannot build guix as part of guix system reconfigure after commit 224d437fb4 on aarch64

[Aiko Kyle <aikokyle@gmail.com>]

On Sat, Jan 1, 2022 at 9:51 PM Leo Famulari <leo@famulari.name> wrote:
>
> Thanks, and I've attached a graph of the same operating system
> declaration from the same revision of Guix but for x86_64, along with
> rendered images of both graphs.
>
> The graphs clearly show that xorg-server is provided in two places on
> aarch64. The question is why?

Thanks Leo for the help on IRC!

What we seem to have figured out is that commit 49599fab56 is almost
certainly the culprit. So the issue is that somehow using
sddm-service-type in %desktop-services on aarch64 instead of
gdm-service-type which is used an x86_64 after that commit results in
xorg-server-service-type being included twice, likely though
gdm-service-type still being included somewhere.
set-xorg-configuration is a potential culprit, although so far I
haven't' been able to make the test pass by modifying the call to
set-xorg-configuration in desktop.tmpl to explicitly pass
sddm-service-type.