Comment 3 for bug 1940288

Problem:
* With an audiodev defined qemu sends data on migration that breaks the receiving end.

Solution:
 * The fix stops sending a state that isn't needed it is fixed on the source) and thereby
   fixes the migration.

Not important for SRU (under libvirt use cases):
 * This did happen to impish because
   - new libvirt/qemu will auto-add -audiodev now
   - old libvirt (pre impish <v7.2.0) did not do so.
 * Old releases seem not to be affected
   - Their libvirt used an environment variable like
         QEMU_AUDIO_DRV=spice
     on guest start

 * Strictly speaking manual use cases of qemu could have
   been affected
   Big chunks of -audiodev for qemu got added in:
    4.0
    https://gitlab.com/qemu-project/qemu/-/commit/33f18cf7
    4.2
    https://gitlab.com/qemu-project/qemu/-/commit/cfc3fef6
    Focal is 4.2, so therefor SRU it up to there.
 * But since it is sound the use cases would be more desktop'ish
   (less likely to migrate) and furthermore without libvirt which takes
   care of so many quirks for migration (also making it less likely
   to be a real case)

The common non-libvirt use cases through lxd-vm and multipass do not do migration yet and even would bump their qemu to a new version that is fixed.

Please understand me - I think there is no reason "against" SRUing this back to Focal.
But someone would have to outline a reasonable use-case in Focal/Hirsute that needs this.

P.S. before Focal it isn't needed as -audiodev didn't exist