Comment 4 for bug 1504366

backtrace:

#0 0xb7adb8bf in std::string::assign(std::string const&) () from /usr/lib/i386-linux-gnu/libstdc++.so.6
#1 0xb7adb93c in std::string::operator=(std::string const&) () from /usr/lib/i386-linux-gnu/libstdc++.so.6
#2 0x08826c6a in EditorPlayerMenu::update (this=0xb32cc80)
    at /var/widelands/ai_persistent_data/src/editor/ui_menus/editor_player_menu.cc:179
#3 0x088275e1 in EditorPlayerMenu::clicked_add_player (this=0xb32cc80)
    at /var/widelands/ai_persistent_data/src/editor/ui_menus/editor_player_menu.cc:226
#4 0x0882bbb9 in boost::_mfi::mf0<void, EditorPlayerMenu>::operator() (this=0xb32d348, t=...)
    at /usr/include/boost/bind/mem_fn_template.hpp:70
#5 0x0882b377 in boost::_bi::list1<boost::reference_wrapper<EditorPlayerMenu> >::operator()<boost::_mfi::mf0<void, EditorPlayerMenu>, boost::_bi::list0> (this=0xb32d350, f=..., a=...) at /usr/include/boost/bind/bind.hpp:253
#6 0x0882afa6 in boost::_bi::bind_t<void, boost::_mfi::mf0<void, EditorPlayerMenu>, boost::_bi::list1<boost::reference_wrapper<EditorPlayerMenu> > >::operator() (this=0xb32d348) at /usr/include/boost/bind/bind_template.hpp:20
#7 0x0882a95f in boost::detail::function::void_function_obj_invoker0<boost::_bi::bind_t<void, boost::_mfi::mf0<void, EditorPlayerMenu>, boost::_bi::list1<boost::reference_wrapper<EditorPlayerMenu> > >, void>::invoke (function_obj_ptr=...)
    at /usr/include/boost/function/function_template.hpp:153
#8 0x08908360 in boost::function0<void>::operator() (this=0xb32d344) at /usr/include/boost/function/function_template.hpp:767
#9 0x08908302 in boost::signals2::detail::call_with_tuple_args<boost::signals2::detail::void_type>::m_invoke<boost::function<void ()>>(void*, boost::function<void ()>&, boost::signals2::detail::unsigned_meta_array<>, std::tuple<>) const (this=0xbfffd6af, func=...,
    args=empty std::tuple) at /usr/include/boost/signals2/detail/variadic_slot_invoker.hpp:92
#10 0x089082e6 in boost::signals2::detail::call_with_tuple_args<boost::signals2::detail::void_type>::operator()<boost::function<void ()>, , 0u>(boost::function<void ()>&, std::tuple<>, mpl_::size_t<0u>) const (this=0xbfffd6af, func=..., args=empty std::tuple)
    at /usr/include/boost/signals2/detail/variadic_slot_invoker.hpp:81
#11 0x08908292 in boost::signals2::detail::variadic_slot_invoker<boost::signals2::detail::void_type>::m_invoke<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> > >(boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> > const&, boost::signals2::detail::void_type const*) const (this=0xbfffd8a0, connectionBody=...)
    at /usr/include/boost/signals2/detail/variadic_slot_invoker.hpp:117
#12 0x089081a7 in boost::signals2::detail::variadic_slot_invoker<boost::signals2::detail::void_type>::operator()<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> > >(boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> > const&) const (this=0xbfffd8a0, connectionBody=...)
    at /usr/include/boost/signals2/detail/variadic_slot_invoker.hpp:110
#13 0x08907ed0 in boost::signals2::detail::slot_call_iterator_t<boost::signals2::detail::variadic_slot_invoker<boost::signals2::detail::void_type>, std::_List_iterator<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> > >, boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> >::dereference() const (this=0xbfffd7a4)
    at /usr/include/boost/signals2/detail/slot_call_iterator.hpp:82
#14 0x089079f1 in boost::iterator_core_access::dereference<boost::signals2::detail::slot_call_iterator_t<boost::signals2::detail::variadic_slot_invoker<boost::signals2::detail::void_type>, std::_List_iterator<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> > >, boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::opti---Type <return> to continue, or q <return> to quit---
onal<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> > >(boost::signals2::detail::slot_call_iterator_t<boost::signals2::detail::variadic_slot_invoker<boost::signals2::detail::void_type>, std::_List_iterator<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> > >, boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()> >, boost::signals2::mutex> > const&) (f=...) at /usr/include/boost/iterator/iterator_facade.hpp:514
#15 0x089072c7 in boost::iterator_facade<boost::signals2::detail::slot_call_iterator_t<boost::signals2::detail::variadic_slot_invoker<boost::signals2::detail::void_type>, std::_List_iterator<boost::shared_ptr<boost::signals2::detail::connection_body<std::pair<boost::signals2::detail::slot_meta_group, boost::optional<int> >, boost::signals2::slot<void (), boost::function<void ()>