Why is Cura adding a feature to top of part while in "Spiralize Outer Contour Mode"?

[Pyropainter 0]

Good evening.

I have recently upgraded Cura 15.04.5 Linux version. When printing a cube in the spiralize mode the slicer adds an unwanted feature to the top of the part. About 4-6 layers from the top of the single walled cube the g-code forces the printer to produce a radius around the perimeter of the part. Which in turn makes the opening at the top smaller. An older version did not do this. The wall was parallel from top to bottom. I liked using the older version to adjust the flow rate percentage to allow for filament diameter discrepancies. With 15.04.5 I am forced to heavily deburr the inside of the part to take measurements. I looked thru the expert settings and did not see a tab or button to avoid Cura adding the unwanted feature. Do you know of a way to shut this off or is this the way the spiralize is intended to work?

Thank you.

[00D00B 58]

Try to uncheck the "Solid Infill Top" case in expert settings and check what happen !