Symmetric tensor function space evaluation and interpolation is wrong

It seems the implementation for evaluation and interpolation of symmetric tensor function space is wrong, while its internal quadrature representation is correct.

from dolfin import *
set_log_level(ERROR)

mesh = UnitSquareMesh(10, 10)
SDG = TensorFunctionSpace(mesh, "DG", 0, symmetry = True)
DG = TensorFunctionSpace(mesh, "DG", 0)

print("Given a constant symmetric tensor ((1, 2), (2, 3)).")
g = Constant(((1.0, 2.0), (2.0, 3.0)))

print("Interpolant to SymTensorDG at (0.5, 0.5): {}".format(interpolate(g, SDG)(0.5, 0.5)))

print("Interpolant to TensorDG at (0.5, 0.5): {}".format(interpolate(g, DG)(0.5, 0.5)))

print("Projection to SymTensorDG at (0.5, 0.5): {}".format(project(g, SDG)(0.5, 0.5)))

print("Projection to TensorDG at (0.5, 0.5): {}".format(project(g, DG)(0.5, 0.5)))

u = interpolate(g, SDG)
v = interpolate(g, DG)
print("L2 difference between interpolants to SymTensorDG and TensorDG: {}".format(assemble(inner(u-v, u-v)*dx)))

u = project(g, SDG)
v = project(g, DG)
print("L2 difference between projections to SymTensorDG and TensorDG: {}".format(assemble(inner(u-v, u-v)*dx)))

u = project(g, SDG)
v = interpolate(u, DG)
print("L2 difference between a SymTensorDG and its interpolant to the bigger space TensorDG: {}".format(assemble(inner(u-v, u-v)*dx)))

u = project(g, SDG)
v = project(u, DG)
print("L2 difference between a SymTensorDG and its projection to the bigger space TensorDG: {}".format(assemble(inner(u-v, u-v)*dx)))

Output:

Given a constant symmetric tensor ((1, 2), (2, 3)).
Interpolant to SymTensorDG at (0.5, 0.5): [ 1.  2.  2.  0.]
Interpolant to TensorDG at (0.5, 0.5): [ 1.  2.  2.  3.]
Projection to SymTensorDG at (0.5, 0.5): [ 1.  2.  3.  0.]
Projection to TensorDG at (0.5, 0.5): [ 1.  2.  2.  3.]
L2 difference between interpolants to SymTensorDG and TensorDG: 1.0
L2 difference between projections to SymTensorDG and TensorDG: 0.0
L2 difference between a SymTensorDG and its interpolant to the bigger space TensorDG: 10.0
L2 difference between a SymTensorDG and its projection to the bigger space TensorDG: 6.40949485492e-33

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