This is brioche made as a large loaf with pleats called “barres” (bars in English.) It looks a bit like the Jewish bread, Challa.
Making it like this is traditional in a western, Atlantic coast region of France called Vendée, especially for Easter and weddings. For weddings, they will even make large brioches that weigh between 20 and 45 pounds (10 and 20 kg) for the traditional “Dance of the Brioche” (sic.)
The brioche makers in Vendée applied for and got EU IGP status for this braided brioche (as of August 2003.)
Many makers of the brioche, however, have decided to opt out of the standards owing to the costs associated with maintaining them. They call their brioche “Brioche Tressée” (braided Brioche) instead. 
 Les Nouvelles de la Boulangerie n°633 – 01/09/2003