Fix touching an invalid parent record for belongs_to

If the parent of a `belongs_to` record fails to be saved due to
validation errors, `touch` will be called on a new record, which causes
an exception (see https://github.com/rails/rails/pull/9320).

Example:

    class Owner < ActiveRecord::Base
      validates_presence_of :name
    end

    class Pet < ActiveRecord::Base
      belongs_to :owner, touch: true
    end

    pet = Pet.new(owner: Owner.new)

    # Before, this line would raise ActiveRecord::ActiveRecordError
    # "can not touch on a new record object"
    pet.save

1 files changed, 1 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/associations/builder/belongs_to.rb b/activerecord/lib/active_record/associations/builder/belongs_to.rb
index 2f2600b7fb..97b1ff18e2 100644
--- a/activerecord/lib/active_record/associations/builder/belongs_to.rb
+++ b/activerecord/lib/active_record/associations/builder/belongs_to.rb
@@ -48,7 +48,7 @@ module ActiveRecord::Associations::Builder
         def belongs_to_touch_after_save_or_destroy_for_#{name}
           record = #{name}
 
-          unless record.nil?
+          unless record.nil? || record.new_record?
             record.touch #{options[:touch].inspect if options[:touch] != true}
           end
         end