group line_items by [customer,variant] in bulk/coop/packing_sheets

lib/reporting/reports/bulk_coop/packing_sheets.rb

@@ -5,7 +5,9 @@ module Reporting
     module BulkCoop
       class PackingSheets < Base
         def query_result
-          table_items.group_by(&:order).values
+          table_items.group_by do |item|
+            [item.order.customer, item.variant]
+          end.values
         end
 
         def columns