Non-uniform scaled blocks shading is wrong in V6

Rhino Rhino for Windows
1

if Blocks are scaled non uniformly the shading is wrong as in the screenshot below. Confirmed on two machines, in V5 it works fine.
Latest SR

blockshade
blockshade1391×718 79.1 KB

2

Thanks for the report. Filed as https://mcneel.myjetbrains.com/youtrack/issue/RH-46983