Panera Bread Co. said Tuesday Ron Shaich will again become sole chief executive of the bakery-café chain when Bill Moreton, currently co-CEO and president, transitions to the role of executive vice chairman on Aug. 1. Shaich and Moreton, who have been co-CEOs since March last year, said the transition was being made so Moreton, who will remain involved in management, would have more time to attend to “a family matter.”