bug#56288: Pitivi can't be started

[Josselin Poiret]

Hello Lily and Christian,

This is unfortunately the usual gdk-pixbuf SVG loader not being found,
since it is part of librsvg.  Some details are described in [1] already,
but to summarize:  we need to propagate gdk-pixbuf so that the
search-path GDK_PIXBUF_MODULE_FILE is properly set for the profile.

Hence, I can reproduce the issue with
--8<---------------cut here---------------start------------->8---
guix shell --pure pitivi -- pitivi
--8<---------------cut here---------------end--------------->8---

but the following launches pitivi properly (didn't check further)
--8<---------------cut here---------------start------------->8---
guix shell --pure pitivi gdk-pixbuf hicolor-icon-theme adwaita-icon-theme -- 
pitivi
--8<---------------cut here---------------end--------------->8---

I think it's very impractical that we have to do this for all packages
that wish to load SVG files via gdk-pixbuf, because it's technical and
not a concern that upstream developers document, since they don't
encounter such behavior.

[1] https://debbugs.gnu.org/cgi/bugreport.cgi?bug=52044#41
    (87zgozy59x.fsf@jpoiret.xyz)

HTH,
-- 
Josselin Poiret