Fix SoD runes

The previous code always got the rune ID for the rune applied to
the gear in the equipment slot, not necessarily the rune ID
applied to a piece of gear in your bags.  This fixes it to always
get the correct rune ID.

ItemRack/ItemRack.lua

@@ -31,10 +31,41 @@ function ItemRack.IsCata()
 	return wowtoc > 40000 and wowtoc < 50000
 end
 
+-- [[ Season of Discovery Runes ]]
 function ItemRack.IsEngravingActive()
 	return C_Engraving and C_Engraving.IsEngravingEnabled()
 end
 
+do
+	if ItemRack.IsEngravingActive() then
+		function ItemRack.AppendRuneID(bag, slot)
+			if slot then
+				if C_Engraving.IsInventorySlotEngravable(bag, slot) then
+					local rune_info = C_Engraving.GetRuneForInventorySlot(bag, slot)
+					if rune_info then
+						return ":runeid:"..tostring(rune_info.skillLineAbilityID)
+					else
+						return ":runeid:0"
+					end
+				else
+					return ""
+				end
+			else
+				if C_Engraving.IsEquipmentSlotEngravable(bag) then
+					local rune_info = C_Engraving.GetRuneForEquipmentSlot(bag)
+					if rune_info then
+						return ":runeid:"..tostring(rune_info.skillLineAbilityID)
+					else
+						return ":runeid:0"
+					end
+				else
+					return ""
+				end
+			end
+		end
+	end
+end
+
 local GetContainerNumSlots, GetContainerItemLink, GetContainerItemID, GetContainerItemCooldown, GetContainerItemInfo, GetItemCooldown, PickupContainerItem, ContainerIDToInventoryID
 if C_Container then
 	GetContainerNumSlots = C_Container.GetContainerNumSlots
@@ -648,30 +679,6 @@ function ItemRack.GetIRString(inputString,baseid,regular)
 	return string.match(inputString or "", (baseid and (regular and ItemRack.iSPatternBaseIDFromRegular or ItemRack.iSPatternBaseIDFromIR) or ItemRack.iSPatternRegularToIR)) or 0
 end
 
--- [[ Season of Discovery Runes ]]
-if ItemRack.IsEngravingActive() then
-	function ItemRack.AppendRuneID(bag, slot)
-		local inv_slot
-		if slot then
-			local item_id = GetContainerItemID(bag, slot)
-			if item_id then
-				inv_slot = C_Item.GetItemInventoryTypeByID(item_id)
-			end
-		else
-			inv_slot = bag
-		end
-		if inv_slot and C_Engraving.IsEquipmentSlotEngravable(inv_slot) then
-			local rune_info = C_Engraving.GetRuneForEquipmentSlot(inv_slot)
-			if rune_info then
-				return ":runeid:"..tostring(rune_info.skillLineAbilityID)
-			else
-				return ":runeid:0"
-			end
-		end
-		return ""
-	end
-end
-
 -- itemrack itemstring updater.
 -- takes a saved ItemRack-style ID and returns an updated version with the latest player level and spec injected, which helps us update outdated IDs saved when the player was lower level or different spec
 function ItemRack.UpdateIRString(itemRackID)