[regression] vaapivideomemory: failed to copy partial memory

Commit dd428cc4 breaks my videos with the following error:

ERROR       vaapivideomemory gstvaapivideomemory.c:584:gst_vaapi_video_memory_copy: failed to copy partial memory (unsupported operation)

I'm trying to pinpoint and create a repeatable stream to upload that consistently breaks it.