Tourists in the narrow streets of Paris's historic centre next month may find themselves dodging swarms of servers with trays of coffee and croissants, as a long-defunct waitering contest is revived.Running will be banned as they each bear a tray with a croissant, a coffee and a glass of water over a two-kilometre (1.2 miles) route through the tight medieval streets of the Marais district -- all, hopefully, without spilling a drop.