His rags-to-riches immigrant journey and good business sense crowned Juvenal Chavez the king of Latino supermarkets in the Bay Area, but now the CEO is fighting a harsh attack on the reputation of his 21-store Mi Pueblo Foods grocery chain. Mi Pueblo stunned some of its more than 3,000 employees last month when it told them it had joined E-Verify, a Department of Homeland Security program that screens the immigration status of new hires. Now, with union activists accusing Chavez of betraying his own undocumented immigrant roots and threatening a consumer boycott if he doesn't pull out of E-Verify by...