Python traceback:

Assertion failed: _cdata->_last_update == _cdata->_next_update at line 1756 of panda/src/pgraph/pandaNode.I
Traceback (most recent call last):
  File "/usr/share/panda3d/direct/showbase/ShowBase.py", line 1676, in __igLoop
    self.graphicsEngine.renderFrame()
AssertionError: _cdata->_last_update == _cdata->_next_update at line 1756 of panda/src/pgraph/pandaNode.I
:task(error): Exception occurred in PythonTask igLoop
Traceback (most recent call last):
  File "Tut-Looking-and-Gripping.py", line 136, in <module>
    run()              #Run the simulation
  File "/usr/share/panda3d/direct/showbase/ShowBase.py", line 2529, in run
    self.taskMgr.run()
  File "/usr/share/panda3d/direct/task/Task.py", line 502, in run
    self.step()
  File "/usr/share/panda3d/direct/task/Task.py", line 460, in step
    self.mgr.poll()
  File "/usr/share/panda3d/direct/showbase/ShowBase.py", line 1676, in __igLoop
    self.graphicsEngine.renderFrame()
AssertionError: _cdata->_last_update == _cdata->_next_update at line 1756 of panda/src/pgraph/pandaNode.I



gdb traceback (with assert-abort 1, only relevant part):

#3  0x00007ffff3e5b14d in PandaNodePipelineReader::get_off_clip_planes (this=0x7fffffffc5a8) at panda/src/pgraph/pandaNode.I:1756
No locals.
#4  0x00007ffff3e37d5f in CullTraverserData::apply_transform_and_state (this=0x7fffffffc590, trav=0x1abeba8) at panda/src/pgraph/cullTraverserData.cxx:65
        node_state = {<PointerToBase<RenderState>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x7ffff7e3c9b0}, <No data fields>}, <No data fields>}
#5  0x00007ffff3e33ca6 in CullTraverser::traverse (this=0x1abeba8, data=...) at panda/src/pgraph/cullTraverser.cxx:210
        node_effects = 0x18bccd8
        fog = 0x7fffffffc570
        node_reader = 0x7fffffffc5a8
        fancy_bits = 4
#6  0x00007ffff3e3413e in CullTraverser::traverse_below (this=0x1abeba8, data=...) at panda/src/pgraph/cullTraverser.cxx:289
        next_data = {_node_path = {_next = 0x7fffffffc750, _start = {<PointerToBase<NodePathComponent>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x0}, <No data fields>}, <No data fields>}, 
            _node = {<PointerToBase<PandaNode>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x18d32c8}, <No data fields>}, <No data fields>}}, _node_reader = {_object = 0x18d32c8, _current_thread = 0xa24e68, _cdata = 0x18d3358, 
            static _type_handle = {_index = 470, static _none = {_index = 0, static _none = <same as static member of an already seen type>}}}, _net_transform = {<PointerToBase<TransformState>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, 
                _void_ptr = 0x7ffff7e3ccc8}, <No data fields>}, <No data fields>}, _state = {<PointerToBase<RenderState>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x7fffe3dd49f8}, <No data fields>}, <No data fields>}, 
          _view_frustum = {<PointerToBase<GeometricBoundingVolume>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x7fffe3da5350}, <No data fields>}, <No data fields>}, 
          _cull_planes = {<PointerToBase<CullPlanes>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x7ffff7e4ed38}, <No data fields>}, <No data fields>}, _draw_mask = {_word = 4294967295, static _type_handle = {_index = 106, static _none = {
                _index = 0, static _none = <same as static member of an already seen type>}}}}
        i = 1
        children = {_down = {<PointerToBase<CopyOnWriteObj1<ov_multiset<PandaNode::DownConnection, std::less<PandaNode::DownConnection> >, TypeHandle> >> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, 
                _void_ptr = 0x7ffff7e3d030}, <No data fields>}, <No data fields>}}
        num_children = 4
        node = 0x1332ed8
        this_node_hidden = false
        node_reader = 0x7fffffffc768
        node_effects = 0x93db58
        has_decal = false
#7  0x00007ffff3e33d85 in CullTraverser::traverse (this=0x1abeba8, data=...) at panda/src/pgraph/cullTraverser.cxx:228
        node_effects = 0x93db58
        fog = 0x0
        node_reader = 0x7fffffffc768
        fancy_bits = 2
#8  0x00007ffff3e33ae6 in CullTraverser::traverse (this=0x1abeba8, root=...) at panda/src/pgraph/cullTraverser.cxx:168
        data = {_node_path = {_next = 0x0, _start = {<PointerToBase<NodePathComponent>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x7ffff7e3d1f8}, <No data fields>}, <No data fields>}, 
            _node = {<PointerToBase<PandaNode>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x1332ed8}, <No data fields>}, <No data fields>}}, _node_reader = {_object = 0x1332ed8, _current_thread = 0xa24e68, _cdata = 0x1332f68, 
            static _type_handle = {_index = 470, static _none = {_index = 0, static _none = <same as static member of an already seen type>}}}, _net_transform = {<PointerToBase<TransformState>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, 
                _void_ptr = 0x7ffff7e3ccc8}, <No data fields>}, <No data fields>}, _state = {<PointerToBase<RenderState>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x7fffe3dd49f8}, <No data fields>}, <No data fields>}, 
          _view_frustum = {<PointerToBase<GeometricBoundingVolume>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x7fffe3da5350}, <No data fields>}, <No data fields>}, 
          _cull_planes = {<PointerToBase<CullPlanes>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x7ffff7e4ed38}, <No data fields>}, <No data fields>}, _draw_mask = {_word = 4294967295, static _type_handle = {_index = 106, static _none = {
                _index = 0, static _none = <same as static member of an already seen type>}}}}
#9  0x00007ffff4374dbe in GraphicsEngine::do_cull (cull_handler=0x7fffffffc9d0, scene_setup=0x1aa1b58, gsg=0x146cfe8, current_thread=0xa24e68) at panda/src/display/graphicsEngine.cxx:1106
        dr = 0x16209b8
        timer = {_collector = @0x1620bb0, _thread = {_client = 0xa243e0, _index = 0}}
        trav = 0x1abeba8
#10 0x00007ffff43762b2 in GraphicsEngine::cull_to_bins (this=0x93dd18, win=0x146bd68, dr=0x16209b8, current_thread=0xa24e68) at panda/src/display/graphicsEngine.cxx:1412
        cull_handler = {<CullHandler> = {_vptr.CullHandler = 0x7ffff571b9f0}, _cull_result = {<PointerToBase<CullResult>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x1aa1a88}, <No data fields>}, <No data fields>}}
        cbobj = 0x0
        timer = {_collector = @0x12487654, _thread = {_client = 0x7fffe3da5200, _index = -13840}}
        gsg = 0x146cfe8
        cull_result = {<PointerToBase<CullResult>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x1aa1a88}, <No data fields>}, <No data fields>}
        scene_setup = {<PointerToBase<SceneSetup>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x1aa1b58}, <No data fields>}, <No data fields>}
#11 0x00007ffff4375d54 in GraphicsEngine::cull_to_bins (this=0x93dd18, wlist=..., current_thread=0xa24e68) at panda/src/display/graphicsEngine.cxx:1347
        dr_reader = 0x0
        camera = {_head = {<PointerToBase<NodePathComponent>> = {<PointerToVoid> = {<MemoryBase> = {<No data fields>}, _void_ptr = 0x7ffff7e45bd0}, <No data fields>}, <No data fields>}, _backup_key = 0, _error_type = NodePath::ET_ok, static _max_search_depth = 7000, 
          static _type_handle = {_index = 467, static _none = {_index = 0, static _none = <same as static member of an already seen type>}}}
        aci = {_M_node = 0x7fffe3da51c8}
        dr = 0x16209b8
        i = 0
        timer = {_collector = @0x146c058, _thread = {_client = 0xa243e0, _index = 0}}
        num_display_regions = 3
        win = 0x146bd68
        timer = {_collector = @0x7ffff587c070, _thread = {_client = 0xa243e0, _index = 0}}
        already_culled = {<std::map<NodePath, DisplayRegion*, std::less<NodePath>, pallocator_single<std::pair<NodePath const, DisplayRegion*> > >> = {_M_t = {
              _M_impl = {<pallocator_single<std::_Rb_tree_node<std::pair<NodePath const, DisplayRegion*> > >> = {<std::allocator<std::_Rb_tree_node<std::pair<NodePath const, DisplayRegion*> > >> = {<__gnu_cxx::new_allocator<std::_Rb_tree_node<std::pair<NodePath const, DisplayRegion*> > >> = {<No data fields>}, <No data fields>}, _type_handle = {_index = 25, static _none = {_index = 0, static _none = <same as static member of an already seen type>}}}, 
                _M_key_compare = {<std::binary_function<NodePath, NodePath, bool>> = {<No data fields>}, <No data fields>}, _M_header = {_M_color = std::_S_red, _M_parent = 0x7fffe3da51c8, _M_left = 0x7fffe3da51c8, _M_right = 0x7fffe3da51c8}, 
                _M_node_count = 1}}}, <No data fields>}
        wi = {_M_current = 0x146ca90}
#12 0x00007ffff437a4d8 in GraphicsEngine::WindowRenderer::do_frame (this=0x93ddd0, engine=0x93dd18, current_thread=0xa24e68) at panda/src/display/graphicsEngine.cxx:2389
        timer = {_collector = @0x7ffff587c030, _thread = {_client = 0xa243e0, _index = 0}}
        holder = {_mutex = 0x93dec8}
#13 0x00007ffff4373a24 in GraphicsEngine::render_frame (this=0x93dd18) at panda/src/display/graphicsEngine.cxx:733
        holder = {_mutex = 0x93df70}
        wi = {_M_current = 0x146c848}
        lti = {_M_current = 0x0}
        new_windows = {<ordered_vector<PointerTo<GraphicsOutput>, IndirectLess<GraphicsOutput> >> = {_compare = {<No data fields>}, 
            _vector = {<std::vector<PointerTo<GraphicsOutput>, pallocator_array<PointerTo<GraphicsOutput> > >> = {<std::_Vector_base<PointerTo<GraphicsOutput>, pallocator_array<PointerTo<GraphicsOutput> > >> = {
                  _M_impl = {<pallocator_array<PointerTo<GraphicsOutput> >> = {<std::allocator<PointerTo<GraphicsOutput> >> = {<__gnu_cxx::new_allocator<PointerTo<GraphicsOutput> >> = {<No data fields>}, <No data fields>}, _type_handle = {_index = 22, static _none = {
                          _index = 0, static _none = <same as static member of an already seen type>}}}, _M_start = 0x146c840, _M_finish = 0x146c848, _M_end_of_storage = 0x146c848}}, <No data fields>}, <No data fields>}}, <No data fields>}
        ti = {_M_node = 0x1}
        current_thread = 0xa24e68
        cache = 0x1858900
        global_clock = 0xa75b58