Update polygon.py

Author: lin-toto

cyaron/polygon.py

@@ -150,7 +150,7 @@ def simple_polygon(points):
             raise Exception("source point is not a list")
         random.shuffle(points)
         if len(points) <= 3:
-            return points
+            return Polygon(points)
         # divide by points[0], points[1]
         divide_line = [points[1][1] - points[0][1],
                        points[0][0] - points[1][0],