Bug#746578: libpam-systemd: for upgrade safety, swap or-dependency to systemd-shim|systemd-sysv

[Josh Triplett]

Package: libpam-systemd
Followup-For: Bug #746578

Zack Weinberg wrote:
> The desired state for jessie is that systemd-sysv and sysvinit-core
> should be coinstallable, with an alternatives-like mechanism for
> deciding which package actually provides init (if this can be done with
> actual alternatives for /sbin/init, that would be ideal, but I suspect
> it cannot be that simple).
> 
> I will be filing another bug against systemd-sysv and sysvinit-core to
> that effect, but as an immediate stopgap measure to prevent breakage,
> libpam-systemd should swap its or-dependency on
> systemd-sysv|systemd-shim so that systemd-shim is first.  That will
> prevent upgrades of *unrelated* packages from changing the running init
> system.

Switching that dependency around will break upgrades on systems that
have the "systemd" package installed and running as init via kernel
command-line argument (without systemd-sysv installed).

- Josh Triplett