Wrong tessellation of self-intersecting contour

[bishopnator]

I tested a little your library and I created a case which is incorrectly tessellated. I attached a test file - it contains the problematic contour. First line contains number of vertices and then followed vertices (x, y, z values split by spaces).
contour3.txt

I use the LibTess2 library with doubles instead of floats (TESSreal type). The problematic intersection is between edge (2-1) and edge (75-76) (numbers are the indices of vertices). I tried also to debug the the code in sweep.c but I didn't find exactly where the problem is. If all vertices are slightly rotated around z-axis (like by 5 degrees) than the tessellation is correct.

note: option TESS_CONSTRAINED_DELAUNAY_TRIANGULATION changes the output triangles, but it produces same filled area

The wrong tessellation:

[EvanBalster]

See this comment describing a much simpler error case. #37 (comment)

I uploaded some source code that doesn't seem to exhibit that bug.

[chris0e3]

With my patch from issue #48 applied I get this:

I.A.I.I.