Bug#1029491: unblock: steam-installer/1:1.0.0.75+ds-4

[Simon McVittie]

Package: release.debian.org
Severity: normal
User: release.debian.org at packages.debian.org
Usertags: unblock
X-Debbugs-Cc: steam-installer at packages.debian.org
Control: affects -1 + src:steam-installer

Please hint src:steam-installer into testing when its age reaches
an appropriate point, despite britney thinking it is uninstallable.
This replaces all binary packages of src:steam (which I suppose is
technically a tiny transition, but it's self-contained and is effectively
a continuation of src:steam). src:steam has now been removed from testing
as a result of its disappearance from unstable.

[ Reason ]
The proprietary parts of Steam require both amd64 and i386 libraries,
most notably glibc and Mesa, and will not work correctly on either a
pure amd64 system or a pure i386 system. The older steam:i386 package
was i386-only, resulting in a long-standing bug that it was installable
on a pure i386 system but wouldn't actually work correctly (#992533) and
also not pulling in its correct dependencies on amd64 systems (although
in practice amd64 desktops would typically have most of them anyway).

steam-installer:amd64 correctly has both amd64 and i386 dependencies,
using the standard workaround of going via a Multi-Arch: foreign package
that is only built on i386 (the same technique as nvidia-graphics-drivers
and older versions of nss-mdns). However, britney evaluates installability
by looking at each architecture in isolation, and therefore thinks that
the steam:i386 and steam-installer:amd64 packages are uninstallable.

The old steam:i386 is also not visible in Appstream-based UIs like GNOME
Software and KDE Discover, and fixing that required a trip through NEW
for multiarch reasons. I took the opportunity to make it a pure installer
package in contrib (which downloads the proprietary launcher on-demand,
with strong validation against a hard-coded sha256), instead of directly
shipping a proprietary binary and being in non-free as a result.

[ Impact ]
If steam-installer is not allowed to migrate to testing, users of Debian 12
who want to install Steam will have to install it via Flatpak (which is
unsupported by Valve and has technical limitations due to its sandboxing)
or from Valve's third-party apt repository (which requires trusting
Valve-supplied code to be run as root, and for historical reasons uses
Recommends for some dependencies that should really be Depends).

[ Tests ]
Installed successfully on a bookworm VM system as a new installation,
and on unstable + real hardware as an upgrade.

[ Risks ]
This is low-risk: it's a leaf package containing very little code (the
actual proprietary Steam client has always been external to Debian and
self-updating, both src:steam-installer and the old src:steam are just
installers/launchers).

I am likely to continue to monitor Steam closely during the lifetime of
Debian 12 as a result of some consultancy work (and also wanting to play
games on a Debian system!) so I will be on the lookout for regressions.

Thanks,
    smcv