Sorry for the release backtrace... :-\

Program received signal SIGSEGV, Segmentation fault.
0x0000000000b9dcd2 in std::_Rb_tree<Widelands::Ware_Index, std::pair<Widelands::Ware_Index const, unsigned char>, std::_Select1st<std::pair<Widelands::Ware_Index const, unsigned char> >, std::less<Widelands::Ware_Index>, std::allocator<std::pair<Widelands::Ware_Index const, unsigned char> > >::begin (this=0x130)
    at /usr/include/c++/4.6/bits/stl_tree.h:660
660				      (this->_M_impl._M_header._M_left));
(gdb) bt
#0  0x0000000000b9dcd2 in std::_Rb_tree<Widelands::Ware_Index, std::pair<Widelands::Ware_Index const, unsigned char>, std::_Select1st<std::pair<Widelands::Ware_Index const, unsigned char> >, std::less<Widelands::Ware_Index>, std::allocator<std::pair<Widelands::Ware_Index const, unsigned char> > >::begin (this=0x130)
    at /usr/include/c++/4.6/bits/stl_tree.h:660
#1  0x0000000000b9ce8e in std::map<Widelands::Ware_Index, unsigned char, std::less<Widelands::Ware_Index>, std::allocator<std::pair<Widelands::Ware_Index const, unsigned char> > >::begin (this=0x130)
    at /usr/include/c++/4.6/bits/stl_map.h:319
#2  0x0000000000bab7c8 in Widelands::DismantleSite::count_returned_wares (building=0xb050ef0, res=...)
    at /home/xxx/widelands/widelands/src/logic/dismantlesite.cc:148
#3  0x0000000000bab438 in Widelands::DismantleSite::init (this=0xb050ef0, egbase=...)
    at /home/xxx/widelands/widelands/src/logic/dismantlesite.cc:114
#4  0x0000000000bab2f8 in Widelands::DismantleSite::DismantleSite (this=0xb050ef0, gdescr=..., 
    egbase=..., c=..., plr=..., loading=false, former_buildings=...)
    at /home/xxx/widelands/widelands/src/logic/dismantlesite.cc:86
#5  0x0000000000af4afa in Widelands::Editor_Game_Base::warp_dismantlesite (this=0x7fffffffaf50, c=..., 
    owner=1 '\001', loading=false, former_buildings=...)
    at /home/xxx/widelands/widelands/src/logic/editor_game_base.cc:349
#6  0x0000000000b713fe in Widelands::Player::_enhance_or_dismantle (this=0x19b3310, building=0xa187e30, 
    index_of_new_building=...) at /home/xxx/widelands/widelands/src/logic/player.cc:760
#7  0x0000000000b7117b in Widelands::Player::dismantle_building (this=0x19b3310, building=0xa187e30)
    at /home/xxx/widelands/widelands/src/logic/player.cc:726
#8  0x0000000000b226d8 in Widelands::Cmd_DismantleBuilding::execute (this=0xb050eb0, game=...)
    at /home/xxx/widelands/widelands/src/logic/playercommand.cc:716
#9  0x0000000000af105b in Widelands::Cmd_Queue::run_queue (this=0x7fffffffb170, interval=1375, 
    game_time_var=@0x7fffffffafb0: 876376) at /home/xxx/widelands/widelands/src/logic/cmd_queue.cc:132
#10 0x0000000000bdf29f in Widelands::Game::think (this=0x7fffffffaf50)
    at /home/xxx/widelands/widelands/src/logic/game.cc:624
#11 0x0000000000ca49cf in Interactive_Base::think (this=0x272c5e0)
    at /home/xxx/widelands/widelands/src/wui/interactive_base.cc:379
#12 0x0000000000ccc243 in Interactive_Player::think (this=0x272c5e0)
    at /home/xxx/widelands/widelands/src/wui/interactive_player.cc:261
#13 0x0000000000dbfd95 in UI::Panel::do_think (this=0x272c5e0)
    at /home/xxx/widelands/widelands/src/ui_basic/panel.cc:585
#14 0x0000000000dbf2cf in UI::Panel::run (this=0x272c5e0)
    at /home/xxx/widelands/widelands/src/ui_basic/panel.cc:205
#15 0x0000000000bdeec1 in Widelands::Game::run (this=0x7fffffffaf50, loader_ui=0x7fffffffae20, 
    start_game_type=Widelands::Game::NewNonScenario)
    at /home/xxx/widelands/widelands/src/logic/game.cc:577
#16 0x0000000000adb1d5 in WLApplication::new_game (this=0x16c43e0)
    at /home/xxx/widelands/widelands/src/wlapplication.cc:2033