['facet'] crushes for RT vector element and higher polynomial degrees

[Johannes Storn]

The code below works for polynomial degree = 1 but crushes for higher degrees

from dolfin import *

mesh = UnitSquareMesh(1,1)

polydegree = 1
RT_elem = VectorElement('RT', mesh.ufl_cell(),polydegree)['facet']
RT = FunctionSpace(mesh,RT_elem)

print 'polydegree = 1 worked'

polydegree = 2
RT_elem = VectorElement('RT', mesh.ufl_cell(),polydegree)['facet']
RT = FunctionSpace(mesh,RT_elem)

print 'polydegree = 2 worked'