Yep! Single vertex bug. Looking via the Ruby API I find:
- The large outer Face doesn’t recognize the smaller one as an inner loop; it runs all the way underneath it.
- The smaller Face appears to be OK, but…
- There is a duplicate, garbled Face whose outer loop encloses both the small (void) area and the smaller Face. Its outer loop traces Edges in the order numbered in the attached image, in effect creating a bow-tie.
