this continued for a while, until one day @alexziebart, the editor-in-chief at wow insider, mentioned using it for the do-over purpose to @mumper, the lead content designer at blizzard. mumper's response can be summed up as "wait what huh? you can do that?" and within days, there was a hotfix and wild pets no longer re-spawned when you killed your browser. this prompted much wailing on the forums, with absolute universal agreement that it was always used by everyone only to help out friends, that it was a social feature that belonged in the game, and that nobody never ever would dream of using it as a cheat to undo their own clumsiness in attempting a capture.
i has a dubious.
now along come the patch 5.2 notes. looking through them, i see the following:
assuming the game ends up working the way the notes say (not always a safe assumption with pet battles, i have found), here's how i interpret this: if you want to hold a pet for a friend while they're on their way over, blizzard is okay with that. in fact, they won't even force you to alt-f4 - you can just flee the battle and take a small health penalty. however, if you accidently kill a pet you wanted to capture, too feckin' bad. it's gone for good. i'm guessing that if you kill the first pet, his friends won't somehow re-span either. not sure how it'll work if you kill the second or third pet but not the first.
sounds like a reasonable approach to encourage cooperation among players while discouraging cheating. we shall see how many salute it when it goes up the flagpole.