Add default shipping category during object creation; revert forms

app/controllers/spree/admin/products_controller_decorator.rb

@@ -30,6 +30,11 @@ Spree::Admin::ProductsController.class_eval do
     @show_latest_import = params[:latest_import] || false
   end
 
+  def new
+    @object.shipping_category = DefaultShippingCategory.find_or_create
+    super
+  end
+
   def create
     delete_stock_params_and_set_after do
       super

app/views/spree/admin/products/_shipping_category_form.html.haml

@@ -1,4 +1,4 @@
 = f.field_container :shipping_categories do 
   = f.label :shipping_category_id, t(:shipping_category)
-  = f.collection_select(:shipping_category_id, Spree::ShippingCategory.all, :id, :name, {:include_blank => false, :selected => DefaultShippingCategory.find_or_create.id}, {:class => 'select2 fullwidth'})
+  = f.collection_select(:shipping_category_id, Spree::ShippingCategory.all, :id, :name, {:include_blank => false}, {:class => 'select2 fullwidth'})
   = f.error_message_on :shipping_category_id

app/views/spree/admin/shipping_methods/_form.html.haml

@@ -53,7 +53,7 @@
       = f.field_container :categories do
         - Spree::ShippingCategory.all.each do |category|
           = label_tag do
-            = check_box_tag('shipping_method[shipping_categories][]', category.id, category == DefaultShippingCategory.find_or_create)
+            = check_box_tag('shipping_method[shipping_categories][]', category.id, @shipping_method.shipping_categories.include?(category))
             = category.name
             %br/
         = error_message_on :shipping_method, :shipping_category_id