I want to rotate half circle mask around cursor placed in a center, but final rotation looks strange. 

[![enter image description here][1]][1]

Is this current limitation of masks or is there anything that I can do better to create simple rotation?

(I tried to ad last anchor point of previous circle in a hope it will be calculated as circle shape, but same result.)

Thank you


  [1]: https://i.sstatic.net/CLINn.gif