Bug#989554: Add argyll dependency

[Simon McVittie]

Control: severity -1 normal

On Mon, 14 Jun 2021 at 21:46:30 +0900, Hideki Yamane wrote:
> On Mon, 07 Jun 2021 13:36:17 +0000 Age Bosma <age.bosma at protonmail.com> wrote:
> > The colour calibration functionality gnome-control-center will
> > happily start the lengthy process of colour testing, only the fail at
> > the end with the error:
> > 
> > "Tools required for calibration are not installed"
> > 
> > This without specifying which tools exactly.

I can see that this is annoying, but I don't think it's release-critical.
Many users of gnome-control-center use it sucessfully without ever having
carried out colour calibration. normal severity, or maybe important, seems
more proportionate.

There is already an upstream issue report at
https://gitlab.gnome.org/GNOME/gnome-control-center/-/issues/1194
saying that the check for argyll should happen before the slow process
of colour testing. If you want to contribute an implementation of that,
I'm sure the upstream developers would appreciate the help.

> > Installing the argyll package solves the issue.
> 
>  It seems that we can pull it via Recommends is enough as below.

Recommends is for "packages that would be found together with this one
in all but unusual installations". Does that really apply here, or would
a Suggests be more appropriate?

argyll has an installed size of around 100M, which is a significant
fraction of the size of the GNOME desktop environment, so I don't think
we necessarily want to be pulling it in by default.

>  But its git repo is a bit confusing, should I patch it to 3.38.4-1
>  in unstable or more updated version 3.38.6-1 in repo?

If you are making changes targeted at GNOME 40 (currently in experimental
due to the freeze, but will go to unstable after Debian 11 is released) then
the debian/master branch is correct.

If this is release-critical for Debian 11 (which I don't think it is,
but perhaps other GNOME team members disagree), then the debian/unstable
branch (which I've just updated) is the correct starting point for
preparing an update for testing/unstable.

Thanks,
    smcv