Fix for Adjustment#repair_adjustments_associations_on_create

When the item gets deleted before after_commit runs.

I ran into this while working on some changes where some tax
adjustments would get created and destroyed in the same transaction.

core/app/models/spree/adjustment.rb

@@ -184,7 +184,7 @@ def require_promotion_code?
  end
 
  def repair_adjustments_associations_on_create
- if adjustable.adjustments.loaded? && !adjustable.adjustments.include?(self)
+ if adjustable.adjustments.loaded? && !adjustable.adjustments.include?(self) && Spree::Adjustment.exists?(id)
  Spree::Deprecation.warn("Adjustment #{id} was not added to #{adjustable.class} #{adjustable.id}. Add adjustments via `adjustable.adjustments.create!`. Partial call stack: #{caller.select { |line| line =~ %r(/(app|spec)/) }}.", caller)
  adjustable.adjustments.proxy_association.add_to_target(self)
  end

core/spec/models/spree/adjustment_spec.rb

@@ -193,6 +193,16 @@ def create_adjustment
  adjustment = create_adjustment
  expect(adjustable.adjustments).to include(adjustment)
  end
+
+ context 'when the adjustment is destroyed before after_commit runs' do
+ it 'does not repair' do
+ expect(Spree::Deprecation).not_to receive(:warn)
+ Spree::Adjustment.transaction do
+ adjustment = create_adjustment
+ adjustment.destroy!
+ end
+ end
+ end
  end
 
  context 'when adjustable.adjustments is not loaded' do