old_contents: 
  class ValidationError(Exception):
      def __init__(self, message):
          self.message = message
  
      def __unicode__(self):
          return self.message
  
  
  class ValidationErrors(Exception):
      '''A container for a dict of validation errors.'''
      def __init__(self, errors):
          self.errors = errors
  
new_contents: 
  class ValidationError(Exception):
      def __init__(self, message):
          self.message = message
  
      def __unicode__(self): # pragma: no cover
          return self.message
  
  
  class ValidationErrors(Exception):
      '''A container for a dict of validation errors.'''
      def __init__(self, errors):
          self.errors = errors
  
subject: Tweak for coverage