nvidia-driver/stretch-backports effectively uninstallable?

[Felix Geyer]

Hi,

It seems nvidia-driver from stretch-backports is effectively uninstallable
if one of the lib*-mesa packages is present.

Steps to reproduce:
* Minimal stretch chroot
* apt install libqt5gui5 (or anything else that depends on libegl1-mesa)
* apt install -t stretch-backports nvidia-driver

The result is:
> The following packages will be REMOVED:
>    libegl1-mesa (13.0.6-1+b2)
>    libgl1-mesa-glx (13.0.6-1+b2)
>    libqt5gui5 (5.7.1+dfsg-3+b1)

I think what happens is that apt selects libegl1 (from stretch-backports)
which conflicts with the libegl1-mesa from stretch.
So apt decides to remove libegl1-mesa and all its reverse-deps.

Installation likely would work if apt selected the *-glvnd-nvidia packages
instead but it doesn't seem to consider that.


I'm wondering how the libglvnd backport is supposed to work given that all
its binary packages conflict with the lib*-mesa counterparts.

Felix