Unfortunately prior to Christmas on the last maintenance that Blizz did, this got broken, now wether it was intentional or not, I'm not sure. More than likely others have bitched enough about people holding upgrade battles for friends or doing the relog trick to start a battle over again to either swap out a pet or change the spell line up. Needless to say I was upset because I found an upgrade for my husband who was batteling not even 50 yards away from me, I did the /exit trick and the battle pet never repsawned. We figured it was a glitch so when he found an upgrade for me he did the /camp trick with the same results. It will be interesting to see what happens with rolling restarts tomorrow as to wether this does get fixed with that or if even after the next official maintenance if it stays broken.