broken mesh after remove_orphaned_nodes() #993
Description
In many cases remove_orphaned_nodes() works well, but on the example t3.py from the Gmsh-python tutorial it causes problems
import meshio
mesh=meshio.read('t3.msh') # https://gitlab.onelab.info/gmsh/gmsh/-/blob/master/tutorial/python/t3.py
mesh.write('t3_OK.vtu')
#mesh.remove_lower_dimensional_cells() # intended use, but not needed to demonstrate problem with remove_orphaned_nodes()
mesh.remove_orphaned_nodes()
mesh.write('t3_trouble.vtu')