The collective scramble to move as much physical copper as possible to the U.S. before the imposition of import tariffs is creating shortages in the rest of the world.London Metal Exchange (LME) stocks have fallen to nearly two-year lows with time-spreads flaring into backwardation as inventory drains away.This tariff trade will continue until U.S. President Donald Trump's administration makes up its mind whether to add copper to the lengthening list of metals subject to penal import duties…