NYPD allegedly told school to keep quiet about recovered knife

NYPD allegedly told school to keep quiet about recovered knife
The NYPD wants the flow of weapons found in city schools out of sight and out of mind. Yet another knife was recovered at a Manhattan school last week — but NYPD officials commanded staffers to shut up about it, sources told The Post. A 17-year-old girl threatened to attack a classmate with a knife…