A Republican Party rule aimed at preventing Democratic plants was too late to stop a committeeman from being elected to represent the 19th Ward on the city’s South Side.An state appeals court found a bylaw prohibiting ward and township committeemen from holding office if they recently voted in another party’s primary infringed upon voter rights when it was enacted after ballots were already being cast for the March 2016 Republican primary election.The 1st District Appellate Court ruled that while …