corners[1:]]
cor_d = [(float(a[0] * b[0] + a[1] * b[1]) / (sqrt(a[0] ** 2 + a[1] ** 2) *
sqrt(b[0] **2 + b[1] ** 2)), a[0] * b[1] - b[0] * a[1], c) for a, b, c in cor_d]
- cor_d = sorted([(copysign(acos(a), b), c) for a, b, c in cor_d])
+ cor_d = sorted([(copysign(acos(min(a, 1)), b), c) for a, b, c in cor_d])
corners = [corners[0]] + [c for _, c in cor_d]
return (_lines(corners, 0) + [(corners[0], corners[3]),
(corners[1], corners[2])],