qemu-system-ppc assertion "!mr->container" failed

Hi,

I'm trying to run the NetBSD/macppc 8.2 installer (which is 32-bit ppc) in qemu-system-ppc
version 5.2.0, and I'm hitting this assertion failure quite a bit into the "unpacking sets" 
part of the installation procedure, unpacking from the install iso image.

Qemu is run on a NetBSD/amd64 9.1 host system.  The stack backtrace from the core file is

Program terminated with signal SIGABRT, Aborted.
#0  0x000078859a36791a in _lwp_kill () from /usr/lib/libc.so.12
[Current thread is 1 (process 1)]
(gdb) where
#0  0x000078859a36791a in _lwp_kill () from /usr/lib/libc.so.12
#1  0x000078859a3671ca in abort () from /usr/lib/libc.so.12
#2  0x000078859a2a8507 in __assert13 () from /usr/lib/libc.so.12
#3  0x000000015a3c19c0 in memory_region_finalize ()
#4  0x000000015a3fef1c in object_unref ()
#5  0x000000015a3feee6 in object_unref ()
#6  0x000000015a374154 in address_space_unmap ()
#7  0x000000015a276551 in pmac_ide_atapi_transfer_cb ()
#8  0x000000015a150a59 in dma_blk_cb ()
#9  0x000000015a46a1c7 in blk_aio_complete ()
#10 0x000000015a5a617d in coroutine_trampoline ()
#11 0x000078859a264150 in ?? () from /usr/lib/libc.so.12
Backtrace stopped: Cannot access memory at address 0x7884894ff000
(gdb) 

I start qemu with this small script:

---
#!/bin/sh

MEM=3g
qemu-system-ppc \
        -M mac99,via=pmu \
        -m $MEM  \
        -nographic \
        -drive id=hda,format=raw,file=disk.img \
        -L pc-bios \
        -netdev user,id=net0,hostfwd=tcp::2223-:22,ipv6=off \
        -net nic,model=rtl8139,netdev=net0 \
        -boot d \
        -cdrom NetBSD-8.2-macppc.iso
---

and boot the install kernel with "boot cd:ofwboot.xcf".  If someone wants
to replicate this I can provide more detailed instructions to repeat the
procedure I used to start the install.

Any hints about what more to look for?

Regards,

- Håvard