use Cluster Mode without audio tracks

Hi people,

I am trying to transcode a DVD-Image with dvd:rip cluster mode.

Transcode does not recognize the audio track format, so I disabled audio and
only want to transcode video.

But if video chunks are finished the cluster deamon tries to merge
audio/video and stops with error because there is no audio track.

If I transcode video locally (same options, but no cluster mode) everything
is fine.

Is this a bug or am I doing something wrong?