TOKYO (Reuters) - Asian stock markets retreated again on Wednesday, extending a rout that began last week as U.S. political uncertainty exacerbated worries over slowing global economic growth. FILE PHOTO: Men look at stock quotation boards outside a brokerage in Tokyo, Japan, December 5, 2018. REUTERS/Issei Kato Investors were unnerved by the U.S. federal government partial shutdown and President Donald Trump’s hostile stance toward the Federal Reserve chairman. U.S.