Error with a vector of uncopyable elements?

[ethannicholas]

When I try to compile this code:

#include <pybind11/pybind11.h>
#include <pybind11/stl.h>

class Uncopyable {
    Uncopyable(const Uncopyable& other) = delete;
};

class Test {
    std::vector<Uncopyable> vec;
};

Test& test() {
  abort(); // unimplemented
}

PYBIND11_MODULE(testmodule, m) {
  pybind11::class_<Test>(m, "Test");
  m.def("test", &test, pybind11::return_value_policy::reference);
}

I receive a long string of template instantiation errors, ending with:

Test.cpp:18:5: note: in instantiation of function template specialization 'pybind11::module_::def<Test &(*)(), pybind11::return_value_policy>' requested here
  m.def("test", &test, pybind11::return_value_policy::reference);
    ^
Test.cpp:5:5: note: 'Uncopyable' has been explicitly marked deleted here
    Uncopyable(const Uncopyable& other) = delete;
    ^

Since I'm specifying return_value_policy::reference, it seems like the fact that the vector is uncopyable shouldn't matter. Is this a bug, or am I doing something wrong?