The following two bags can also contain that specific battle pet:
https://www.wowhead.com/item=142447/torn-sack-of-pet-supplies
https://www.wowhead.com/item=151638/leprous-sack-of-pet-supplies

And this one as well:
https://www.wowhead.com/item=184866/grummlepouch

Thanks! Looks like wowhead doesn't have any drops for those bags, which is why they don't show up on the Porcupette page.

Actually, come to think of it this may be because they use pushed loot (loot toasts) instead of regular containers? (IIRC)

I'll update the database anyway, but if the detection isn't working that might warrant looking into on a separate occasion.