distros.conf: update backports configuration

backports have been integrated into the main archive

Signed-off-by: Andreas Beckmann <anbe@debian.org>
Makefile: perform python syntax check in {master,slave}-bin, too

Signed-off-by: Andreas Beckmann <anbe@debian.org>
kpr/db_setup_*.conf: catch warning: database package not installed

Signed-off-by: Andreas Beckmann <anbe@debian.org>
add/update copyright notices for myself

Signed-off-by: Andreas Beckmann <anbe@debian.org>
dwke: fix splitting the section list

the [global] section setting can have a wrapped multiline value

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