Bug#746578: More systemd fallout :-/

[Ian Jackson <ijackson@chiark.greenend.org.uk>]

In #746578, a user requests that the dependency from libpam-systemd to
systemd be changed from
   systemd-sysv | systemd-shim
to
   systemd-shim | systemd-sysv

The maintainers of libpam-systemd have rejected this change.  I would
like the TC to set out the applicable principle(s), and overrule the
maintainer in this case.


As I understand it from reading the threads in the bug and on
debian-devel, the effect of this would be:

 * New jessie installations would still get systemd.

 * squeeze->jessie upgrades which are not already using systemd would
    not be switched silently to systemd but would use systemd-shim
    instead.

 * Attempts to upgrade non-systemd systems in some other circumstances
   would no longer switch silently to systemd.


My starting point is the following principle:

 * Users should not be switched automatically when upgrading.

   This is especially important given the controversy, and our
   commitment to support multiple init systems.

   This would also be analogous with other similar decisions.  For
   example, if the default desktop for jessie remains XFCE, we do not
   expect users upgrading from wheezy to have GNOME replaced with
   XFCE.  If we were to change the default MTA or nameserver or
   syslogd, we would not expect to replace the installed MTA or
   nameserver or syslogd on existing systems.


There is an argument that it would be nice to prompt an upgrading user
about switching.  Personally I think this is doubtful and even if
accepted it raises a number of further questions.

But it is academic for jessie as we do not have a sane technical
approach for prompting and it is too late to develop one now.


Having settled on the above principle, I think it follows that the
dependency ought to be changed.


IMO the argument is ripe for the TC.  We are just going round in
circles on -devel.

Thanks.
Ian.