SOMETIMES a single moment captures France’s struggle to reform. The “grand social conference” on July 7th-8th was one. The third under President François Hollande, it is a ritual where the government meets employers and unions to discuss possible labor reforms. The president and the prime minister both make a speech. Meetings go on for a day and a half. Yet as the conference began this week, two of the big five unions walked out.The departure of the communist-backed Confédération Générale du Travail and Force Ouvrière, which between them account for nearly half of elected works councils in France, was a direct snub to Mr Hollande. The Socialist president was elected in 2012 promising to end confrontational labor relations and introduce a consensus-based “social dialogue”. But the unions were cross because, just before the conference, Manuel Valls, the prime minister, made concessions to employers to stop them boycotting the talks: he postponed a controversial new retirement rule that awards extra pension credits for “demanding work”.Their boycott does not put an end to labor talks. Those still left will begin discussions over expanding…