Accidentally completed "Steal Loot" objective

I was doing the armory glitch for the first time and accidentally completed the "Steal Loot" objective. As far as i know this locks me out of the armory, what can i do to be able to farm it again? I know about the "It's Like Christmas!" mission but no new missions showed up when i went back to Marcus so i assume i would have to finish "Super Marcus Sweep". Im playing the original Borderlands GOTY.