Vader's head, hand, and feet go OVER this black area. I think it actually is an unfinished matte! The lines are too straight across that pole area to be simply unfinished set. They tried to cover it up by starting a matte, but not finishing I guess. If they wanted it to be interpreted as the bridge, they wouldn't have had to rotoscope Vader's body parts over it, they could have just splashed more black and be done with it.

One could go with either Angel's awesome fix, or just unrotoscope Vader from in front of it and have it be the interpretation TMBTM saw.

Thanks to Bobocop, you can watch this over and over and over and over...
http://www.youtube.com/watch?v=FjICkQF4w4o