fai-mirror, fai-cd and backports

[Andreas Heinlein]

Hello,

we are currently using FAI to install Ubuntu 12.04 on our clients, using
a Debian Wheezy server with FAI 4.2.5. We are also using fai-cd to
create installation media for some offsite machines.

We need to take some specific packages from the backports repository,
namely hplip.

If I add 'hplip/precise-backports' to the packages file, this works for
the normal installation, but it does not for the CDs. The reason is that
fai-mirror creates a new repository named 'cskoeln', so FAI/apt cannot
find the 'precise-backports' repo when running from CD.
I could use apt-pinning instead by creating a respective file in
${target}/etc/apt/preferences.d right before task_instsoft. This would,
however, make it neccessary to make fai-mirror use the same pinning when
creating the mirror. I have not found a way of doing that short of
directly editing the script, which I would rather not do.

Any ideas how to solve this cleanly?

Thanks,
Andreas