Handling rvalue function arguments

I'm trying to wrap a C++ function that accepts an rvalue argument (std::unique_ptr<T>&&) and consumes it. In the docs it is mentioned that unique_ptrs are not allowed as arguments, because the instance might still be used.
However, when passing the pointer as an rvalue reference, this should work anyway - the holder pointer still exists and re-accessing it in python should throw. That's the way it worked in boost::python at least. There, it was possible to release auto_ptrs. Accessing the python object subsequently, was just throwing:

Python argument types in
    test_move_arg_bp.access(Item)
did not match C++ signature:
    access(Item)

An example illustrating the pybind11 issue and a running boost::python example is available here.

Start with the advanced/smart_ptrs.html#std-unique-ptr documentation and the linked rvalue-argument comparison, then reproduce the pybind11 and boost::python examples. Trace how a std::unique_ptr&& argument is handled and verify that consuming it prevents subsequent access through the Python object.