It is broken since commit c6196440.

Reported-by: Michael Fritscher <michael@fritscher.net>
Tested-by: Michael Fritscher <michael@fritscher.net>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>