===== TITLE

libpam-systemd to switch alternate dependency ordering

===== WEB SUMMARY

The committee decided that systemd-shim should be the first listed
alternative dependency of libpam-systemd instead of systemd-sysv.

===== EMAIL INTRO

The technical committe was asked in #746578 to override the ordering
of the alternative dependencies on systemd-sysv and systemd-shim to
prefer the installation of systemd-shim in cases where sysvinit-core
was already installed.

===== EMAIL EPILOGUE

The committee would like to thank everyone who participated in the
discussion of #746578, especially Josh Triplett, Serge Hallyn, Sam
Hartman, Cameron Norman, and Michael Biebl.

===== DECISION

Rationale (Constitution 6.1(5)):

1. Currently libpam-systemd (which is pulled in by quite a few
   dependency chains) Depends on `systemd-sysv | systemd-shim (>= 8-2)'.

2. The effect of this is that installing some packages which depend
   (directly or indirectly) on libpam-systemd can cause a user's init
   system to be switched to systemd, even on systems where a user has
   deliberately chosen not to use the default init system, and even
   when the switch is unnecessary.

3. Swappping the order of these dependencies would avoid that and has
   no harmful effect:

4. In particular, on systems that already have systemd-sysv installed,
   libpam-systemd will still not pull in systemd-shim, thus minimizing
   the risk of breakage on systemd systems.  However, on systems that
   intentionally do not have systemd-sysv installed, the installation
   of libpam-systemd will then prefer to pull in systemd-shim and keep
   the installed init system rather than switching to systemd-sysv.

Decision (Constitution 6.1(4)):

5. We therefore overrule the decision of the maintainer of
   libpam-systemd binary package.  The Depends entry
      systemd-sysv | systemd-shim (>= 8-2)
   should be replaced by
      systemd-shim (>= 8-2) | systemd-sysv

6. For the avoidance of doubt, we do not intend to set this specific
   syntax in stone.  For example, if in future libpam-systemd needs to
   depend on a later systemd-shim, or needs a versioned rather than
   unversioned dependency on systemd-sysv, that is fine and would not
   contradict our decision.

Release (Constitution 6.1(5)):

7. Our advice is that this change should be in jessie.  If necessary,
   this view should be conveyed to the Release Team, after the change
   is in unstable, by filing an unblock request in the usual way.