Edges in parallel UG are broken

When compiled in parallel mode the edges in a parallel dune-uggrid are broken. More specifically: In a 3d grid obtained from successive local refinement of a simplex the leaf grid contains edges that have a non-trivial intersection. E.g. they intersect in a point that is neither a vertex of one or the other edge. When compiled in sequential mode this does not happen. Moreover, the number of total edges is larger in parallel mode while the number of elements, faces, and vertices is the same. One can also observe, that the centers of the elements are different.

The attached example demonstrates the issue: uggrid-failure.cc . It works nicely when dune is set to sequential mode and the edge count is different.

I was unsure if this should be files here or for dune-uggrid. Since I have a vague memory that UG does not provide edges by itself and that they are implemented in the dune bindings I picked dune-grid.