vtkUnstructuredGridToExplicitStructuredGrid is not parallel friendly
This illustrated by failure in the test pvcs.ExplicitStructuredGridReal
when running with MPI. The issue is that vtkUnstructuredGridToExplicitStructuredGrid
is given a non-empty UG only on root node (since input dataset in vtu file, which is only read on rank 0). Subsequently, vtkUnstructuredGridToExplicitStructuredGrid produces bogus grid on rank > 0 and that causes the vtkExplicitStructuredGridSurfaceFilter
to raise errors down the pipe. The test has been disabled for now.