no sound in spice when VNC enabled

Running Fedora32 with virt-manager → libvirt → qemu  I noticed that I got no sound in my spice client. The VM is configured with a SPICE-server and a QXL display, and in addition a VNC display.

Apparently when I remove the VNC display, then the sound is routed just fine to the spice client: I can hear it, and `G_MESSAGES_DEBUG=all remote-viewer --spice-debug  spice://localhost:5900` mentions SpicePlaybackChannel and SpiceRecordChannel. With the VNC server configured, such messages are missing, and I cannot hear the sound (which is sent by the guest OS to the virtual hardware).

What is in the libvirt logs (/var/log/libvirt/qemu/${guest}.log) ?

If VNC is enabled, then libvirt sets QEMU_AUDIO_DRV=none unless  /etc/libvirt/qemu.conf is set to allow output to host audio.

Clearly this doesn't do the right thing when SPICE is present at the same time as VNC, but that's libvirt's fault rather than QEMU.

So if this is libvirt's fault, can we close this ticket here? Has anybody already reported this to in the libvirt bug tracker?

[Expired for QEMU because there has been no activity for 60 days.]