Code review comment for lp:~ldeo-magma/dolfin/devfixes

Some tests are failing for me:

In file included from /home/garth/code/fenics/dolfin.d/trunk.d/testing/local/include/dolfin/mesh/dolfin_mesh.h:29:0,
                 from /home/garth/code/fenics/dolfin.d/trunk.d/testing/local/include/dolfin.h:12,
                 from /home/garth/code/fenics/dolfin.d/trunk.d/testing/test/unit/mesh/cpp/test.cpp:23:
/home/garth/code/fenics/dolfin.d/trunk.d/testing/local/include/dolfin/mesh/MeshValueCollection.h: In member function ‘dolfin::MeshValueCollection<T>& dolfin::MeshValueCollection<T>::operator=(const dolfin::MeshValueCollection<T>&) [with T = int]’:
/home/garth/code/fenics/dolfin.d/trunk.d/testing/test/unit/mesh/cpp/test.cpp:248:9: instantiated from here
/home/garth/code/fenics/dolfin.d/trunk.d/testing/local/include/dolfin/mesh/MeshValueCollection.h:335:3: error: no return statement in function returning non-void [-Werror=return-type]
/home/garth/code/fenics/dolfin.d/trunk.d/testing/local/include/dolfin/mesh/MeshValueCollection.h: In member function ‘dolfin::MeshValueCollection<T>& dolfin::MeshValueCollection<T>::operator=(const dolfin::MeshFunction<T>&) [with T = int]’:
/home/garth/code/fenics/dolfin.d/trunk.d/testing/local/include/dolfin/mesh/MeshValueCollection.h:328:3: error: control reaches end of non-void function [-Werror=return-type]
cc1plus: all warnings being treated as errors