I am working to track down the issue. I believe it is something minor and related to live-images since I pull from debian-nex branch of live-images to build on cgi builder.
Thanks.
If you read the m-l regularly then I just replied to a message also reporting desktop builds produce no image. If you are not a m-l member the issue was with package-lists, namely you can not have the first line
as a logic statement for some reason. I made a
commit to live-images branch debian-next that fixes the issue and
builds should now be working again for desktop images.