Reference to theme_blocks which doesn't exist in Drupal 7

On 234 line of print.pages.inc is the following

$footer = variable_get('site_footer', FALSE) . "\n" . theme('blocks', 'footer');

This produces the error Theme key "blocks" not found. to be recorded in the logs. Looking at the Drupal API docs, the theme_blocks function is not available in Drupal 7.