For the third time, the cops of the NYPD have turned their backs on the mayor of New York. The first time was when Mayor Bill de Blasio arrived at Woodhull Hospital where mortally wounded officers Rafael Ramos and Wenjian Liu had been taken on Dec. 20. The second was when the mayor spoke at Ramos' funeral. The third was at Liu's service on Sunday. Detestation of de Blasio among the NYPD and the cops who came from across the country to stand in solidarity with their slain brothers is broad and deep. And, in a way, de Blasio served...