slave_run: do not run the screen as root

Signed-off-by: Andreas Beckmann <anbe@debian.org>
use screen -ls to check for running screens

Signed-off-by: Andreas Beckmann <anbe@debian.org>
slave_join: use 'script /dev/null' to get a writable tty

avoid

user$ sudo su - piupartss
piupartss$ screen -x
Cannot open your terminal '/dev/pts/42' - please check.

Signed-off-by: Andreas Beckmann <anbe@debian.org>
slave_run: use piuparts.conf to get paths etc.

Signed-off-by: Andreas Beckmann <anbe@debian.org>
slave_run: ensure PIUPARTS_TMPDIR exists

Signed-off-by: Andreas Beckmann <anbe@debian.org>
slave_run: drop ancient trap+mail code

that's useless with daemonized screen

Signed-off-by: Andreas Beckmann <anbe@debian.org>
reorder changelog entries w.r.t. exceptions

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

otherwise checksetup.pl will enter an infinite loop asking for this

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