nifty python build failure

hanslovskyp@saalfelds-ws2 ~/git/nifty/build (git)-[master] % make
[  4%] Built target test_marray
[  8%] Built target test_depth_first_search
[ 13%] Built target test_undirected_graph
[ 17%] Built target test_shortest_path_dijkstra
[ 22%] Built target test_shortest_path_bellman_ford
[ 26%] Built target test_edge_weighted_watersheds
[ 31%] Built target test_breadth_first_search
[ 35%] Built target test_array
Scanning dependencies of target _nifty
[ 37%] Building CXX object src/python/lib/CMakeFiles/_nifty.dir/nifty.cxx.o
[ 40%] Building CXX object src/python/lib/CMakeFiles/_nifty.dir/graph/graph.cxx.o
[ 42%] Building CXX object src/python/lib/CMakeFiles/_nifty.dir/graph/undirected_list_graph.cxx.o
In file included from /home/hanslovskyp/local/include/pybind11/attr.h:13:0,
                 from /home/hanslovskyp/local/include/pybind11/pybind11.h:32,
                 from /home/hanslovskyp/git/nifty/src/python/lib/graph/undirected_list_graph.cxx:1:
/home/hanslovskyp/local/include/pybind11/cast.h: In instantiation of ‘class pybind11::detail::type_caster_base<const nifty::graph::UndirectedGraph<>&>’:
/home/hanslovskyp/local/include/pybind11/cast.h:310:56:   required from ‘class pybind11::detail::type_caster<const nifty::graph::UndirectedGraph<>&, void>’
/home/hanslovskyp/local/include/pybind11/cast.h:836:72:   required by substitution of ‘template<class T> typename std::enable_if<std::integral_constant<bool, ((! pybind11::detail::move_always<T>::value) && (! pybind11::detail::move_if_unreferenced<T>::value))>::value, T>::type pybind11::cast(pybind11::object&&) [with T = const nifty::graph::UndirectedGraph<>&]’
/home/hanslovskyp/local/include/pybind11/cast.h:919:74:   required from ‘T pybind11::object::cast() const & [with T = const nifty::graph::UndirectedGraph<>&]’
/home/hanslovskyp/git/nifty/src/python/lib/graph/export_undirected_graph_class_api.hxx:91:53:   required from ‘nifty::graph::exportUndirectedGraphClassAPI(pybind11::module&, CLS_T&, const string&)::<lambda(pybind11::object)> [with G = nifty::graph::UndirectedGraph<>; CLS_T = pybind11::class_<nifty::graph::UndirectedGraph<> >]’
/home/hanslovskyp/git/nifty/src/python/lib/graph/export_undirected_graph_class_api.hxx:90:28:   required from ‘struct nifty::graph::exportUndirectedGraphClassAPI(pybind11::module&, CLS_T&, const string&) [with G = nifty::graph::UndirectedGraph<>; CLS_T = pybind11::class_<nifty::graph::UndirectedGraph<> >; std::__cxx11::string = std::__cxx11::basic_string<char>]::<lambda(class pybind11::object)>’
/home/hanslovskyp/git/nifty/src/python/lib/graph/export_undirected_graph_class_api.hxx:94:14:   required from ‘void nifty::graph::exportUndirectedGraphClassAPI(pybind11::module&, CLS_T&, const string&) [with G = nifty::graph::UndirectedGraph<>; CLS_T = pybind11::class_<nifty::graph::UndirectedGraph<> >; std::__cxx11::string = std::__cxx11::basic_string<char>]’
/home/hanslovskyp/git/nifty/src/python/lib/graph/undirected_list_graph.cxx:68:85:   required from here
/home/hanslovskyp/local/include/pybind11/cast.h:270:19: error: ‘static pybind11::handle pybind11::detail::type_caster_base<type>::cast(type&&, pybind11::return_value_policy, pybind11::handle) [with type = const nifty::graph::UndirectedGraph<>&]’ cannot be overloaded
     static handle cast(type &&src, return_value_policy policy, handle parent) {
                   ^~~~
/home/hanslovskyp/local/include/pybind11/cast.h:264:19: error: with ‘static pybind11::handle pybind11::detail::type_caster_base<type>::cast(const type&, pybind11::return_value_policy, pybind11::handle) [with type = const nifty::graph::UndirectedGraph<>&]’
     static handle cast(const type &src, return_value_policy policy, handle parent) {
                   ^~~~
/home/hanslovskyp/local/include/pybind11/cast.h:276:19: error: forming pointer to reference type ‘const nifty::graph::UndirectedGraph<>&’
     static handle cast(const type *src, return_value_policy policy, handle parent) {
                   ^~~~
/home/hanslovskyp/local/include/pybind11/cast.h:284:5: error: forming pointer to reference type ‘const nifty::graph::UndirectedGraph<>&’
     operator type*() { return (type *) value; }
     ^~~~~~~~
make[2]: *** [src/python/lib/CMakeFiles/_nifty.dir/build.make:111: src/python/lib/CMakeFiles/_nifty.dir/graph/undirected_list_graph.cxx.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:581: src/python/lib/CMakeFiles/_nifty.dir/all] Error 2
make: *** [Makefile:95: all] Error 2
make  7.35s user 0.60s system 98% cpu 8.092 total