Bot doesn't attack mobs tagged by other mobs

The bot isn't unable to attack Starving Fungal Giant (http://www.wowhead.com/npc=18125/starving-fungal-giant), since it is "tagged" or in combat with another mob which is Sporeggar Spawn (http://www.wowhead.com/npc=18358/sporeggar-spawn)

It does attack them when "Can attack units already in combat" is enabled which is kinda annoying.

The bot should count Starving Fungal Giants as an untagged mob even though it is fighting another npc.