Hi Guix,

this patch fixes compilation issues with the arc-theme on core-updates.

Some questions:

* I cherry-picked a sassc-fix from wip-gnome-upgrades. Is that OK?
* I could not test it: I created a VM with %gnome-services and
arc-theme as a
system package, but it was not available in the gnome-tweak-tool.
Any idea of how to use/test it?

Björn