Oil fell on Wednesday after an industry report showed an unexpected build in U.S. crude inventories, but optimism around the signing of the first phase of a U.S.-China trade deal capped a deeper slide in prices. Wednesday’s decline reversed two days of gains with WTI climbing 1.1% through Tuesday and Brent gaining 1.4% during the period on the expectation that China and the United States, the world’s two biggest crude users, would sign a preliminary agreement that would begin to end their 16-month trade war.