Remove duplicate_extra logic from ProductDuplicator

app/models/spree/product.rb

@@ -261,17 +261,11 @@ module Spree
     end
 
     # for adding products which are closely related to existing ones
-    # define "duplicate_extra" for site-specific actions, eg for additional fields
     def duplicate
       duplicator = Spree::Core::ProductDuplicator.new(self)
       duplicator.duplicate
     end
 
-    # Called by Spree::Product::duplicate before saving.
-    def duplicate_extra(_parent)
-      master.sku = ''
-    end
-
     # use deleted? rather than checking the attribute directly. this
     # allows extensions to override deleted? if they want to provide
     # their own definition.

lib/spree/core/product_duplicator.rb

@@ -15,8 +15,6 @@ module Spree
         # don't dup the actual variants, just the characterising types
         new_product.option_types = product.option_types if product.variants?
 
-        # allow site to do some customization
-        new_product.__send__(:duplicate_extra, product) if new_product.respond_to?(:duplicate_extra)
         new_product.save!
         new_product
       end
@@ -38,7 +36,7 @@ module Spree
       def duplicate_master
         master = product.master
         master.dup.tap do |new_master|
-          new_master.sku = "COPY OF #{master.sku}"
+          new_master.sku = ""
           new_master.deleted_at = nil
           new_master.images = master.images.map { |image| duplicate_image image }
           new_master.price = master.price

spec/lib/spree/core/product_duplicator_spec.rb

@@ -64,7 +64,7 @@ describe Spree::Core::ProductDuplicator do
     expect(new_product).to receive(:deleted_at=).with(nil)
     expect(new_product).to receive(:master=).with(new_variant)
 
-    expect(new_variant).to receive(:sku=).with("COPY OF 12345")
+    expect(new_variant).to receive(:sku=).with("")
     expect(new_variant).to receive(:deleted_at=).with(nil)
     expect(new_variant).to receive(:images=).with([new_image])
     expect(new_variant).to receive(:price=).with(variant.price)

spec/models/spree/product_spec.rb

@@ -16,17 +16,6 @@ module Spree
           expect(clone.master.sku).to eq ''
           expect(clone.images.size).to eq product.images.size
         end
-
-        it 'calls #duplicate_extra' do
-          Spree::Product.class_eval do
-            def duplicate_extra(old_product)
-              self.name = old_product.name.reverse
-            end
-          end
-
-          clone = product.duplicate
-          expect(clone.name).to eq product.name.reverse
-        end
       end
 
       context "product has no variants" do