module ActiveModel::Dirty

def changes_applied

+mutations_from_database+ to +mutations_before_last_save+ respectively.
Clears dirty data and moves +changes+ to +previous_changes+ and
def changes_applied
  unless defined?(@attributes)
    mutations_from_database.finalize_changes
  end
  @mutations_before_last_save = mutations_from_database
  forget_attribute_assignments
  @mutations_from_database = nil
end