The race among the top sellers of crude to the world’s biggest energy-consuming nation got a little tighter last month. Iraq overtook Russia to become the third-largest supplier to China, while Oman edged past Iran in sales of oil to Asia’s biggest economy. Saudi Arabia kept the lead in the race even as its shipments slipped, data from General Administration of Customs in Beijing on Monday show. Cargoes from Angola rose, helping the African producer hold onto the No. 2 spot. China remains the main safeguard against a further price meltdown as a drive to boost its strategic petroleum reserve helps alleviate a market glut. As a shale boom in the U.S. shrinks America’s need for overseas crude, producers are competing to supply the world’s second-biggest oil consumer, which is forecast by the International Energy Agency to account for about a quarter of growth in global demand next year. […]