There's a race in the message delivery against object deletion. Add a
test that triggers it reliably. This test is expected to fail with an
assertion error.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>