$end = $db->selectField( 'revision', 'MAX(rev_id)', false, __FUNCTION__ );
if ( is_null( $start ) || is_null( $end ) ) {
$this->output( "...revision table seems to be empty, nothing to do.\n" );
$end = $db->selectField( 'revision', 'MAX(rev_id)', false, __FUNCTION__ );
if ( is_null( $start ) || is_null( $end ) ) {
$this->output( "...revision table seems to be empty, nothing to do.\n" );