black dots in circle border when drawing with custom pensize

[yonghuming]

i have update the code in screen.py so i can draw images with custom pensize, but the output seems strange.

def circle(self, pos, radius, color, pensize = 1):
        """Draw a circle."""
        pos = round_pos(pos)
        pygame.draw.circle(self._surf, make_color(color), pos, radius, pensize)

then i draw circle with pensize 10

def draw():
    screen.clear()
    screen.draw.circle((400, 300), 300, 'red', 10)

so, you can see there are black dots in circle border

[lordmauve]

This is an pygame/pygame#388, fixed in pygame/pygame#389.