Berlin (dpa) Union Berlin and club president Dirk Zingler have refused to comment on an sarcastic banner held by Bayern Munich fans during the match between both teams on Wednesday evening. “We’re not going to say anything about it,” Union spokesman Christian Arbeit told dpa in response to a corresponding request on Thursday. As part of a protest against external investors coming into the league, Bayern fans held a banner saying: “It’s better to be a winner than to express criticism of the Stasi pig who is courting investor.” Zingler was also shown with a pig’s nose in a Stasi uniform. The bac…