Error while editing a node with multiple select vocabulary

Modify the code on taxonomy.module to defend against duplicate for array $terms.
This avoid mysql error message when editing a node.
Function taxonomy_node_save

  if (is_array($terms)) {
    foreach ($terms as $term) {
      if (is_array($term)) {
        foreach ($term as $tid) {
          if ($tid) {
	    $typed_term_tid = $tid;
	    if (!isset($inserted[$typed_term_tid])) {
	      db_query('INSERT INTO {term_node} (nid, tid) VALUES (%d, %d)', $nid, $tid);
	      $inserted[$typed_term_tid] = TRUE;
	    }
          }
        }
      }
      else if (is_object($term)) {
	$typed_term_tid = $term->tid;
	if (!isset($inserted[$typed_term_tid])) {
	  db_query('INSERT INTO {term_node} (nid, tid) VALUES (%d, %d)', $nid, $term->tid);
	  $inserted[$typed_term_tid] = TRUE;
	}
      }
      else if ($term) {
	$typed_term_tid = $term;
	if (!isset($inserted[$typed_term_tid])) {
	  db_query('INSERT INTO {term_node} (nid, tid) VALUES (%d, %d)', $nid, $term);
	  $inserted[$typed_term_tid] = TRUE;
	}
      }
    }
  }