Upside-down corner stairs are incorrectly orientated.

Upside-down corner stairs are incorrectly orientated.

What I expected to happen was that the upside-down would be placed normally.

What actually happened was that the stairs were incorrectly orientated, in this case backwards.

To reproduce the bug, place an upside-down stair (this works for all types of stairs), and then place another upside-down stair on the side.