TrinityCore/TrinityCore — pull request #8997 by Souler (2013-01-19 14:42:55+00:00)
Title: Spells/Mage: Mages should be able to see everything while on Invisibility

Since 4.X the hablility Invisibility (http://old.wowhead.com/spell=66) only makes the mage inivible, making him able to see other people (not other mages in invisibility) and only detectable by units with a detection aura.