Avoid unnecessary save

Actually, the variant factory is still adding an extra save. We should refactor Variant to avoid that.. but the afternoon slump has got me.

app/models/spree/variant.rb

@@ -282,8 +282,8 @@ module Spree
 
       dup.tap do |variant|
         variant.price = price
-        variant.save!
         variant.source_variants = [self]
+        variant.stock_items << Spree::StockItem.new(variant:)
         variant.owner_id = owner_id
         variant.on_demand = on_demand
         variant.on_hand = on_hand

spec/models/spree/variant_spec.rb

@@ -1018,13 +1018,9 @@ RSpec.describe Spree::Variant do
                child: enterprise,
                permissions_list: [:create_sourced_variants])
       }
+      let(:variant) { create(:variant, price: 10.95, on_demand: false, on_hand: 5) }
 
       it "clones the variant, retaining a link to the source" do
-        variant.price = 10.95
-        variant.save!
-        variant.on_demand = false
-        variant.on_hand = 5
-
         sourced_variant = variant.create_sourced_variant(user)
 
         expect(sourced_variant.source_variants).to eq [variant]