project function should collapse subspaces

The below code throws an error because Functions cannot be created used subspaces (views). It should be fixable if project checks if the FunctionSpace is a subspace, and if so collapses it.

from dolfin import *
mesh=UnitSquare(10, 10)
U = FunctionSpace(mesh, "CG", 1)
V = FunctionSpace(mesh, "CG", 1)
W=U*V
f1=Function(W.sub(0))
f1.vector()[:]=1.0
f2=project(f1, W.sub(1))