Combine zones with the same label on the item page

For example, the "Red Knitted Beanie with Wig" occupies two different
"Hat" zones: one for behind the head, and one for in front. It's not
useful to split them up!

app/controllers/items_controller.rb

@@ -98,8 +98,9 @@ class ItemsController < ApplicationController
         @preview_error = validate_preview
 
         @all_appearances = @item.appearances
-        @appearances_by_occupied_zone = @item.appearances_by_occupied_zone.
+        @appearances_by_occupied_zone_label =
-          sort_by { |z, a| z.label }
+          @item.appearances_by_occupied_zone.
+          transform_keys(&:label).sort_by { |l, a| l }
         @selected_item_appearance = @preview_outfit.item_appearances.first
 
         @preview_pet_type_options = PetType.where(color: @preview_outfit.color).

app/views/items/show.html.haml

@@ -64,17 +64,17 @@
     .item-zones-info
       %section
         %h3 Occupies
-        - if @appearances_by_occupied_zone.present?
+        - if @appearances_by_occupied_zone_label.present?
           %ul
-            - @appearances_by_occupied_zone.each do |zone, appearances_in_zone|
+            - @appearances_by_occupied_zone_label.each do |label, appearances|
               %li<
-                = zone.label
+                = label
-                - if item_zone_partial_fit? appearances_in_zone, @all_appearances
+                - if item_zone_partial_fit? appearances, @all_appearances
                   = " "
                   %span.zone-species-info{
-                    title: item_zone_species_list(appearances_in_zone)
+                    title: item_zone_species_list(appearances)
                   }<
-                    (#{appearances_in_zone.size} species)
+                    (#{appearances.size} species)
         - else
           %span.no-zones (None)