Romanian factory workers killed two policemen in a rampage on Nov. 15 through Brasov, and the city is now occupied by government troops, the West German newspaper Bild am Sonntag said. It said up to 20,000 workers from three factories rioted after Communist authorities tried to force them to vote in a local election. Some workers stormed the Brasov City Hall and slit the throat of one police guard and beat another to death, the paper said. Meanwhile, the Communist Party postponed a party congress set for Dec. 7-8 until Dec. 14-16, the official news agency Agerpres said. It was not clear if the demonstrations had influenced the decision. Agerpres said the move was taken "in order . . . to prepare the conference in adequate conditions."