Kreeg's Stout Beatdown does not stack with food buff
Current behavior: Kreeg's Stout Beatdown (a consumable one can buy from Stomper Kreeg in Dire Maul after completing a tribute run, grants -5 Intellect and +25 Spirit for 15 minutes) doesn't stack with food buff.
Expected behavior: The buff should stack with food buff (and other buffs, such as Divine Spirit).
Supporting evidence/data: Tested this after a tribute run. Consuming the Kreeg's Stout Beatdown cancels the food buff and vice versa. According to some forums/guides (e.g. [1]), WoWWiki [2] and comments on Wowhead [3], it used to stack until the stacking was removed in WotLK patch 3.3.
[2] https://wowwiki.fandom.com/wiki/Kreeg%27s_Stout_Beatdown ("World of Warcraft: Wrath of the Lich King Patch 3.3.0 (08-Dec-2009): The Spirit buff no longer stacks with other food and spirit buffs.")
[3] https://www.wowhead.com/item=18284/kreegs-stout-beatdown#comments ("3.3 Live, this cancels your food buff and vice versa. Good bye fun drinking mans buff :'(")