autodetect dpkg capability force-unsafe-io

turn the option on if dpkg initially supports it
or after it becomes available during distupgrades

Signed-off-by: Andreas Beckmann <anbe@debian.org>
divert /sbin/sync and link /bin/true there instead

sync within the throwaway chroots is useless but affects the host

Signed-off-by: Andreas Beckmann <anbe@debian.org>
*-dkms: install kernel headers so that a module gets built

Signed-off-by: Andreas Beckmann <anbe@debian.org>
report dkms module build failures

Signed-off-by: Andreas Beckmann <anbe@debian.org>
reorganize Matthias' changelog entry

Signed-off-by: Andreas Beckmann <anbe@debian.org>
lib/db: factor out _get_package_weight()

used for ranking packages that are waiting to be tested

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