how to investigate problem of DUD file not handled by yast ?

This is a follow up of email in opensuse-factory ML (1)

Steps of problem detailed in (2)
* create a DUD file from a new powerpc-utils rpm rebuilt locally
  (note that its release number 9 is greater than 2.1 from DVD)
* start a ppc64le guest (on a ppc64le host) with a qemu script 
  using this generated dud file
* the yast UI remains hung on "Saving bootloader configuration"
  as per bug 1011529 (3) confirm that new rpm is not used.

This is the purpose of this bug to understand why rpm from dud
is not used by yast.

I will upload a data5.tgz tarball with linuxrc and YaST2 logs


(1) https://lists.opensuse.org/opensuse-factory/2016-11/msg00501.html
(2) 
===
$mkdud -c boo1011529_5.dud --dist tw
/home/michel/buildtmp/build-root/standard-ppc64le/home/abuild/rpmbuild/RPMS/ppc64le/powerpc-utils-1.3.2-9.ppc64le.rpm
===
cat ~/bin/qemutrial2
$cat ~/bin/qemutrial2
#!/bin/bash
KERNEL=/home/michel/raid/linux
INITRD=/home/michel/raid/initrd
ISOFILE=/home/michel/raid/openSUSE-Tumbleweed-DVD-ppc64le-Snapshot20161122-Media.iso

cd
disk=raid/l1
rm -f $disk
qemu-img create $disk -f raw 10G
set -x
qemu-system-ppc64 \
-vga std -m 4096 -machine usb=off -cpu host -nographic \
-netdev user,id=qanet0,hostfwd=::10022-:22,hostname=qemu2 -device
virtio-net,netdev=qanet0 \
-device virtio-scsi-pci,id=scsi0 \
-device virtio-scsi-pci,id=scsi1 \
-device scsi-hd,drive=hd1a,bus=scsi0.0 -drive
file=$disk,cache=none,if=none,id=hd1a,serial=mpath1,format=raw \
-device scsi-hd,drive=hd1b,bus=scsi1.0 -drive
file=$disk,cache=none,if=none,id=hd1b,serial=mpath1,format=raw \
-drive media=cdrom,if=none,id=cd0,format=raw,file=${ISOFILE} -device
scsi-cd,drive=cd0,bus=scsi0.0 \
-boot once=d,menu=on,splash-time=5000 \
-smp 8,threads=8 -enable-kvm -no-shutdown \
-monitor stdio -serial pty -S \
-append "linemode=1 linuxrc.log=/var/log/YaST2/linuxrc.log startshell=1
insecure=1 UseSSH=1 SSHPassword=root
DUD=http://stade.lab.toulouse-stg.fr.ibm.com/~normand/boo1011529_5.dud" \
-kernel $KERNEL -initrd $INITRD
===
=== linuxrc output extract:
ok, ip = 10.0.2.15/24
Loading
http://stade.lab.toulouse-stg.fr.ibm.com/~normand/boo1011529_5.dud - 100%
http://stade.lab.toulouse-stg.fr.ibm.com/~normand/boo1011529_5.dud:
adding to installation system
Driver Updates added:
~normand/boo1011529_5.dud
===
(3) https://bugzilla.suse.com/show_bug.cgi?id=1011529
===