Comment 16 for bug 467841

Do you use kernel modesetting? If yes you should not be able even to boot normally, not even talking about starting Xorg, if you have the same problem.
But if i understand correctly the kms driver check if something is actually attached to the port and if not bails out appropriately ;-)
You might be able to tell him to go ahead though.
In any case no modesetting should get you going further (i915.modeset=0 on the kernel command line).