Projection into DG1 x CG1 space looks wrong

The following code:

```
from firedrake import *

L = 2.0
H = 1.0
nlayers = 100
dz = H/nlayers

m = PeriodicIntervalMesh(100, length=L)
mesh = ExtrudedMesh(m, layers=nlayers, layer_height=dz)

#1D spaces in horizontal
IUh0 = FiniteElement("CG", "interval", 2)
IUh1 = FiniteElement("DG", "interval", 1)

#1D spaces in vertical
IUv0 = FiniteElement("CG", "interval", 1)
IUv1 = FiniteElement("DG", "interval", 0)

#Temperature space
V1v_elt = OuterProductElement(IUh1, IUv0)
V1v = FunctionSpace(mesh, V1v_elt)

#Solution variables
oldT = project(Expression(("exp(-((x[0]-1.0)*(x[0]-1.0) + (x[1]-0.5)*(x[1]-0.5))/0.04)")),V1v)

file = File("temp.pvd")

file << oldT
```

produces a field where the slopes in each element go the wrong way. This can most easily be observed by opening the file in Paraview and selecting Filters -> Warp by Scalar, then clicking Apply.

Is something wrong with the numbering perhaps?