Fix summons not attacking foes

git-svn-id: http://svn.net-core.org/repos/t-engine4@1342 51575b47-30f0-44d4-a5cc-537603b46e54

game/modules/tome/ai/summon.lua

@@ -28,6 +28,7 @@ newAI("summoned", function(self)
 	end
 
 	-- Do the normal AI, otherwise follows summoner
+	if self.ai_target.actor == self.summoner then self.ai_target.actor = nil end
 	if self:runAI("target_simple") then
 		return self:runAI(self.ai_real)
 	else