detect_piuparts_issues: detect another tar error

tar: Error is not recoverable: exiting now

Signed-off-by: Andreas Beckmann <anbe@debian.org>
post_*_squeeze-backports: some special handling needed

similarily to experimental we can't easily use
  apt-get dist-upgrade -t squeeze-backports
so maintain a list of packages in the minimal base system that
need to be upgraded in the reference system to bpo to avoid mismatches

Signed-off-by: Andreas Beckmann <anbe@debian.org>
p.conf: add wheezy2bpo2jessie

Signed-off-by: Andreas Beckmann <anbe@debian.org>
lib/conf: expand depends in O(n) instead of O(n^2)

Signed-off-by: Andreas Beckmann <anbe@debian.org>
lib/conf: clarify a variable name

Signed-off-by: Andreas Beckmann <anbe@debian.org>
lib/conf: resolve virtual distros when querying mirror or distro

Signed-off-by: Andreas Beckmann <anbe@debian.org>
p-s: exit gracefully if no sections were found

Signed-off-by: Andreas Beckmann <anbe@debian.org>
TODO: update
TODO: harmonize formatting
Merge remote-tracking branch 'andreas/for-holger' into develop
dont forward private test installation emails to public list
TODO: update
detect_slave_problems: remove check limiting this script to be run on piatti only.
master-bin/prepare_backup: also backup sources.txt.
dwke - Fix error handline for package metric retrieval.

It no longer throws a KeyError when the package is missing from
the distribution. Check explicitly for None.
TODO: remove duplicate entry
archive_old_logs: compress (xz) archived logs

Signed-off-by: Andreas Beckmann <anbe@debian.org>
p-s: include arch in the default tarball name

allows running both amd64 and i386 on the same slave with minimal configuration

Signed-off-by: Andreas Beckmann <anbe@debian.org>
p-m: reindent

Signed-off-by: Andreas Beckmann <anbe@debian.org>
p-m: increase logfile verboseness

Signed-off-by: Andreas Beckmann <anbe@debian.org>