Bug#620249: apt: specific+general pin chooses wrong package version

[John Bazik <jsb@cs.brown.edu>]

Package: apt
Version: 0.7.20.2+lenny2
Severity: normal


I thought I had a pretty good grasp of pinning, but I can't understand the
following behavior.  What I'm trying to do is, for a particular package,
always install the newest package version from either my local archive
OR lenny-backports.

My local archive is oldstable (same as lenny), and I have no target
release defined.

sources.list:
   deb http://mymirror/debian lenny main contrib non-free
   deb http://mymirror/debian-security lenny/updates main contrib non-free
   deb http://mymirror/debian-backports lenny-backports main contrib non
   deb http://mymirror/debian-browncs lenny local

preferences:
   Package: *
   Pin: release a=oldstable
   Pin-Priority: 750

   Package: *
   Pin: release a=lenny-backports
   Pin-Priority: 80

   Package: dovecot-imapd
   Pin: release a=lenny-backports
   Pin-Priority: 750

% apt-cache policy dovecot-imapd
dovecot-imapd:
  Installed: (none)
  Candidate: 1:1.2.15-1~bpo50+1
  Package pin: 1:1.2.15-1~bpo50+1
  Version table:
     1:1.2.15-1~bpo50+1+browncs 750
        750 http://mymirror lenny/local Packages
     1:1.2.15-1~bpo50+1 750
         80 http://mymirror lenny-backports/main Packages
     1:1.0.15-2.3+lenny1 750
        750 http://mymirror lenny/main Packages
        750 http://mymirror lenny/updates/main Packages

The priorities are equal, but the older version from lenny-backports
is the candidate.  I would expect the newer version to be installed.

I tried adding a second specific pin at 750 to oldstable, but then
the package chosen depends on the ordering in the preferences file.

It seems like the specific pin supercedes the package version
comparison, but only in the case that the priorities are equal.

-- Package-specific info:

-- (/etc/apt/preferences present, but not submitted) --


-- (/etc/apt/sources.list present, but not submitted) --


-- System Information:
Debian Release: 5.0.8
  APT prefers oldstable
  APT policy: (750, 'oldstable')
Architecture: i386 (i686)

Kernel: Linux 2.6.26-2-686 (SMP w/4 CPU cores)
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/bash

Versions of packages apt depends on:
ii  debian-archive-keyring 2010.08.28~lenny1 GnuPG archive keys of the Debian a
ii  libc6                  2.7-18lenny7      GNU C Library: Shared libraries
ii  libgcc1                1:4.3.2-1.1       GCC support library
ii  libstdc++6             4.3.2-1.1         The GNU Standard C++ Library v3

apt recommends no packages.

Versions of packages apt suggests:
pn  apt-doc               <none>             (no description available)
ii  aptitude              0.4.11.11-1~lenny1 terminal-based package manager
ii  bzip2                 1.0.5-1+lenny1     high-quality block-sorting file co
ii  dpkg-dev              1.14.31            Debian package development tools
ii  gnome-apt             0.4.9-5            graphical package manager
ii  lzma                  4.43-14            Compression method of 7z format in
ii  python-apt            0.7.7.1+nmu1       Python interface to libapt-pkg
ii  synaptic              0.62.1+nmu1        Graphical package manager

-- debconf-show failed