Incorrect intersections when intersecting vertices

[accounts01]

The following produces no intersections but seems like it should:

intersections(
    new Circle( new Point(2, 3), 1),
    new Polygon( new Point(2, 3), new Point(3, 3), new Point(3, 4), new Point(2, 4) 
);

Intersections should be reported at 3, 3 and 2, 4. It seems that when the intersections occur at the polygon's vertices, they are not reported. Is this a bug or have I misunderstood how to use intersections? Thanks!

[accounts01]

The Polygon.collision function appears to be marred by the same sort of issue. Collisions are not reported if the smaller polygon's vertices are along the larger polygon's edges.