The leaders of Russia, Saudi Arabia and the U.S. each badly miscalculated the pain caused by the collapse in oil prices. Now they are trying to rescue their economies and stave off any political damage at crucial moments for each. The big decline in oil prices—sparked by a Saudi-Russia feud and a sharp drop in demand thanks to the new coronavirus pandemic—has hit all three of the men’s power bases at a moment when the global response to the pandemic threatens to pull their economies into recession. …