MySQL Cursor fetching only one row

My SQL:

CREATE PROCEDURE INV_MIN_PURCHASE_PRICE()
BEGIN
DECLARE done INT;
DECLARE current_inventory_ID INT;
DECLARE cur1 CURSOR FOR SELECT inventory_ID FROM _inventory;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

SET done = 0;
OPEN cur1;

REPEAT

    FETCH cur1 INTO current_inventory_ID;
    UPDATE _debug SET rows=rows+1;

UNTIL done
END REPEAT;

CLOSE cur1;

END;

When I call this procedure MySQL is fetching only one row (_debug rows are increased by 1). Why?? Is it a bug?