For much of May, nearly each and every time that oil prices tanked amid concerns about the deepening U.S.-China trade war, one corner of the market held up: timespreads. The spreads -- the price difference between contracts for immediate delivery and forward ones -- reflected tightness in the physical market, with refineries willing to pay large premiums to secure barrels straight away. As such, the oil curve was in a steep backwardation, where spot crude trades above later contracts. For most of May, oil refiners bid up the front of the oil curve to keep North Sea crude in north-west Europ...