I don't believe to this test!
The new Art version of Sigma has absolutely the same optical design as the old version. The old version was tested by Dxomark and got 12-Mpix of sharpness where is the new version by Dxomark gets only 10-Mpix of sharpness. I suppose that there is a mistake or the copy of the new lens which was tested by Dxomark was defective.
The old version test : http://www.dxomark.com/Lenses/Sigma/Sigma-30mm-F28-EX-DN-Sony-E