I have sung this song my whole life; it was one of my Dad’s favourites. “Va, dis à mes amis” is the way I learnt it.

GerryM’s grammar point is technically adequate, but not idiomatic and therefore wrong. The poet uses the informal second person “tu”, as if addressing a friend. Would you say, “Go to tell Aunt Rhody the old grey goose is dead?” I don’t think so. French people don’t either.