THIS COULD BE A VERY INTERESTING WEEK, with an FOMC statement that may acknowledge problems in the repo market, with the U.K holding a cringe-inducing election, with impeachment momentum continuing despite reservations by some Democrats, and with Mike Bloomberg starting to make a move. But there’s only one issue that could make a major difference for the markets — the U.S.-China trade talks, facing a Dec. 15 deadline. There was surge of euphoria on Oct. 11 when an “agreement