apt wants to downgrade packages with pin-priority less than 1000

[Alon Swartz]

Martin Meredith wrote:
> On Sat, Dec 27, 2008 at 09:14:56PM +0200, Alon Swartz wrote:
>> Hi Guys,
>>
>> Firstly, let me introduce myself, I am one of the developers for TurnKey
>> Linux, an opensource project that develops a family of lightweight
>> installable Ubuntu based Live CD appliances optimized for various
>> server-type tasks.
>>
>> Now, down to business...
>>
>> Summary
>> -------
>>
>> apt will attempt to downgrade an installed package if the pin-priority
>> of the package is greater than 99.
>>
>> apt will not downgrade when pin-priorty is 99 or below because the
>> already installed package automatically gets a priority of 100.
>>
>> According to the apt_preferences manpage (mentioned several times), apt
>> will *never* downgrade a package unless the priority of an available
>> version exceeds 1000.
>>
>> Details
>> -------
>>
>> I came across this issue because our package repository has not yet been
>> updated with the latest package, but the latest package has been
>> installed on the system.
>>
>> Although this shouldn't matter, apt seems to be breaking its own rules
>> (unless I am missing something...)
>>
>> My testing system:
>>     Ubuntu 8.04.1 (Hardy)
>>     apt 0.7.9ubuntu17.1 for i386 compiled on Oct 27 2008 18:11:08
>>
>> # dpkg -s drupal5 |grep Version
>> Version: 5.12-2
>>
>> # cat /etc/apt/preferences
>> Package: drupal5
>> Pin: release o=turnkeylinux
>> Pin-Priority: 999
>>
>> Note: the pin-priority can be anything larger than 99 to reproduce this,
>> and the same situation happens with other packages.
>>
>> # apt-cache policy drupal5
>> drupal5:
>>   Installed: 5.12-2
>>   Candidate: 5.10-3
>>   Package pin: 5.10-3
>>   Version table:
>>  *** 5.12-2 999
>>         100 /var/lib/dpkg/status
>>      5.10-3 999
>>         500 http://archive.turnkeylinux.org hardy-security/universe Packages
>>      5.7-1ubuntu1.1 999
>>         500 http://archive.ubuntu.com hardy-security/universe Packages
>>
>> # apt-get install drupal5
>> ...
>> The following packages will be DOWNGRADED:
>>   drupal5
>>
>> In other words, the installed version is 5.12-2 but apt wants to
>> downgrade to the eariler version 5.10-3.
>>
>> Is this a bug in apt, a bug in the documentation, or am I
>> mis-understanding something?
> 
> Is that the full of your apt preferences? Policy is reporting you've pinned the 
> package by version.
> 
> Can you pastebin your full preferences file, and the output of apt-config dump?
> 
> 

The above mentioned /etc/apt/preferences is my full preferences file.
I have pinned the package to the release origin, not specifying a version.

# grep Origin
/var/lib/apt/lists/archive.turnkeylinux.org_ubuntu_dists_hardy_Release
Origin: turnkeylinux

The output of apt-config dump is available at the following link,
although it looks like a vanilla ubuntu configuration:
http://ubuntu.pastebin.com/f73a5138b

Cheers,
Alon Swartz

-- 
Website: http://www.turnkeylinux.org
Launchpad: https://launchpad.net/~alonswartz