There are some error in rect_util.py

[esdream]

In line 87 and 89 of rect_util.py, there should be

result.shift_xy(-p.x, -p.y)
...
result.shift_xy(p.x, p.y)

instead of result.shift.
By the way, the parameter theta of rotate_about function should be a radian rather than a degree.