Update default scopes with acts_as_paranoid

Fixes an issue where the LineItem :sorted_by_name_and_unit_value scope was not working with removal of the default scopes on line item and variant, which meant that the join in the scope was excluding soft-deleted items that should not have been excluded.

app/models/spree/line_item.rb

@@ -10,7 +10,7 @@ module Spree
     include LineItemBasedAdjustmentHandling
 
     belongs_to :order, class_name: "Spree::Order", inverse_of: :line_items
-    belongs_to :variant, class_name: "Spree::Variant"
+    belongs_to :variant, -> { with_deleted }, class_name: "Spree::Variant"
     belongs_to :tax_category, class_name: "Spree::TaxCategory"
 
     has_one :product, through: :variant
@@ -154,18 +154,6 @@ module Spree
       @preferred_shipment = shipment
     end
 
-    # Remove product default_scope `deleted_at: nil`
-    def product
-      variant.product
-    end
-
-    # This ensures that LineItems always have access to soft-deleted variants.
-    # In some situations, unscoped super will be nil. In these cases,
-    #   we fetch the variant using variant_id. See issue #4946 for more details.
-    def variant
-      Spree::Variant.unscoped { super } || Spree::Variant.unscoped.find(variant_id)
-    end
-
     def cap_quantity_at_stock!
       scoper.scope(variant)
       return if variant.on_demand

app/models/spree/variant.rb

@@ -13,7 +13,8 @@ module Spree
 
     acts_as_paranoid
 
-    belongs_to :product, touch: true, class_name: 'Spree::Product'
+    belongs_to :product, -> { with_deleted }, touch: true, class_name: 'Spree::Product'
+
     delegate_belongs_to :product, :name, :description, :permalink, :available_on,
                         :tax_category_id, :shipping_category_id, :meta_description,
                         :meta_keywords, :tax_category, :shipping_category
@@ -188,13 +189,6 @@ module Spree
       price_in(currency).try(:amount)
     end
 
-    # Product may be created with deleted_at already set,
-    # which would make AR's default finder return nil.
-    # This is a stopgap for that little problem.
-    def product
-      Spree::Product.unscoped { super }
-    end
-
     # can_supply? is implemented in VariantStock
     def in_stock?(quantity = 1)
       can_supply?(quantity)

spec/models/spree/line_item_spec.rb

@@ -190,8 +190,17 @@ module Spree
         end
       end
 
-      it "finds line items sorted by name and unit_value" do
-        expect(o.line_items.sorted_by_name_and_unit_value).to eq([li6, li5, li4, li3])
+      describe "#sorted_by_name_and_unit_value" do
+        it "finds line items sorted by name and unit_value" do
+          expect(o.line_items.sorted_by_name_and_unit_value).to eq([li6, li5, li4, li3])
+        end
+
+        it "includes soft-deleted products/variants" do
+          li3.variant.product.destroy
+
+          expect(o.line_items.reload.sorted_by_name_and_unit_value).to eq([li6, li5, li4, li3])
+          expect(o.line_items.sorted_by_name_and_unit_value.to_sql).to_not match "deleted_at"
+        end
       end
 
       it "finds line items from a given order cycle" do