Problem importing stl cet has coincident vertices

Hello all,
One quick question
I have a proven program that works with stl import. However, when i try to import this file [1] i get the following error

FATAL /build/yade-KKgSmd/yade-1.20.0/pkg/common/Facet.cpp:26 postLoad: Facet has coincident vertices 0 (0 0 0) and 1 (0 0 0)!
FATAL /build/yade-KKgSmd/yade-1.20.0/pkg/common/Facet.cpp:26 postLoad: Facet has coincident vertices 0 (0 0 0) and 1 (0 0 0)!
FATAL /build/yade-KKgSmd/yade-1.20.0/pkg/common/Facet.cpp:26 postLoad: Facet has coincident vertices 2 (0 0 0) and 0 (0 0 0)!

What i dont understand is why. The same file without one tiny shape covering 2 holes passes just fine.

The code i use to import the stl is the following

facets = ymport.stl(name)

  rod1 = O.bodies.append(facets)

  # converts facets to gts (see the other question)

  s = gts.Surface()

  for facet in facets:

     vs = [facet.state.pos + facet.state.ori*v for v in facet.shape.vertices]

     vs = [gts.Vertex(v[0],v[1],v[2]) for v in vs]

     es = [gts.Edge(vs[i],vs[j]) for i,j in ((0,1),(1,2),(2,0))]

     f = gts.Face(es[0],es[1],es[2])

     s.add(f)

  print s.is_closed()

  threshold = 1e-3

  s.cleanup(threshold)

  print s.is_closed()

  assert s.is_closed()

  # use gts to filter spheres

  pred = inGtsSurface(s)

  print "r = ", r

I really appreciate any suggestions
[1] http://dropmefiles.com/hOWA1