old_contents: import urlparse
  
  
  class ValidationError(Exception):
    pass
  
  
  def validate_url(url):
    _url = urlparse.urlsplit(url, 'http')
    if _url.scheme != 'http':
      raise ValidationError("Invalid scheme '%s', should be http" % _url.scheme)
    elif not url.startswith('http://'):
      _url = urlparse.urlsplit('http://%s' % url, 'http')
  
    return _url
  
new_contents: import urlparse
  
  
  class ValidationError(Exception):
    pass
  
  
  def validate_url(url):
    _url = urlparse.urlsplit(url, 'http')
    if _url.scheme != 'http':
      raise ValidationError("Invalid scheme '%s', should be http" % _url.scheme)
  
    return url
  
subject: Return original url