/* this worked, run one line at a time */
$x = Vocabulary::get( 'categories' );
$x->move_term( $x->get_term( 'B' ), $x->get_term( 'F' ), true );
$x->displace_term( 'B', -8 );
$params = array( 6, $x->id, 2 );
$res = DB::query( 'UPDATE {terms} SET mptt_left=mptt_left-? WHERE vocabulary_id=? AND mptt_left > ?', $params );
$res = DB::query( 'UPDATE {terms} SET mptt_right=mptt_right-? WHERE vocabulary_id=? AND mptt_right > ?', $params );
$params = array( 6, $x->id, 2 );
$res = DB::query( 'UPDATE {terms} SET mptt_left=mptt_left+? WHERE vocabulary_id=? AND mptt_left > ?', $params );
$res = DB::query( 'UPDATE {terms} SET mptt_right=mptt_right+? WHERE vocabulary_id=? AND mptt_right > ?', $params );
$x->displace_term( 'B', 9 );

/* this didn't work */
$x->move_term( $x->get_term( 'B' ), $x->get_term( 'F' ), true );