waylandsink: v4l2src-renegotiate failure when using DMABUF

Trying to run the v4l2src-renegitiation test when --io-mode=dmabuf causes a renegotiation error when using waylandsink.

It looks like something similar to DRAIN/ALLOCATION event handling in kmssink sink is needed in waylandsink. Is that true? Would a similar approach (i.e. copying the last buffer content to a non DMABUF backed buffer and submitting it to the wayland compositor) be a reasonable approach for this?