Debian installer segfaults on qemu-system-sparc64

[user ibs]

Distributor ID: Ubuntu
Description: Ubuntu 22.04.3 LTS
Package: qemu-system-sparc
Version: 1:6.2+dfsg-2ubuntu6.17

Also other qemu versions. Filed upstream

usecase: make lab install of debian for sparc64

https://cdimage.debian.org/cdimage/ports/12.0/sparc64/debian-12.0.0-sparc64-NETINST-1.iso
sha256: 89147b9fe060e6f94fc90c788b07f57e988b4c68d7a7b8ef9dd24358364e9593

Steps to reproduce

 Start the installer normally (boot cdrom), use guided all disk partition.
 Installer always segfaults at the same place while installing base system step.

Minimal reproducer so far as prepared by @mjt0k:

wget http://www.corpit.ru/mjt/tmp/sparc64-debian-sid.vmlinuz
wget http://www.corpit.ru/mjt/tmp/sparc64-debian-sid.initrd

qemu-system-sparc64 -nographic -m 1G \
  -kernel sparc64-debian-sid.vmlinuz \
  -initrd sparc64-debian-sid.initrd \
  -append "root=none shell"

In guest:

while true; do dpkg-deb --fsys-tarfile /bin/debian-archive-keyring_2023.4_all.deb | grep fault; done