property type for 'url' entity metadata property should not be 'url'

link_field_item_property_info() defines sub-properties for link fields, and the 'url' property's type is defined as 'url':

  $properties['url'] = array(
    'type' => 'url',
    'label' => t('The URL of the link.'),
    'setter callback' => 'entity_property_verbatim_set',
  );

However, the 'url' type is validated by Entity API with valid_url(). Link module allowed Drupal paths to be entered into the field, eg 'node/1', but this type prevents a path being set programmatically in the field value because it doens't validate as a url.