(gdb) bt
#0  0x00002b5b3b853738 in __lll_mutex_lock_wait () from /lib/libpthread.so.0
#1  0x00002b5b3b84f901 in _L_mutex_lock_100 () from /lib/libpthread.so.0
#2  0x00002b5b3b84f2a5 in __pthread_mutex_lock (mutex=0x149e640) at pthread_mutex_lock.c:81
#3  0x00002aaaad17211a in gst_object_get_parent (object=0x126e5a0) at gstobject.c:841
#4  0x00002aaaad172848 in gst_object_get_path_string (object=0x126e5a0) at gstobject.c:1086
#5  0x00002aaaac69bf5f in _wrap_gst_object_tp_str (self=0x10faaf0) at gstobject.override:66
#6  0x00002b5b3b55ac82 in _PyObject_Str (v=0x149e640) at Objects/object.c:406
#7  0x00002b5b3b566514 in PyString_Format (format=0x1038d50, args=0x1026ea8) at Objects/stringobject.c:4653
#8  0x00002b5b3b52d2ce in binary_op1 (v=0x1322ec0, w=0x0, op_slot=32) at Objects/abstract.c:398
#9  0x00002b5b3b52dd81 in binary_op (v=0x149e640, w=0x0, op_slot=998599184, op_name=0xffffffffffffffff <Address 0xffffffffffffffff out of bounds>)
    at Objects/abstract.c:450
#10 0x00002b5b3b59a746 in PyEval_EvalFrameEx (f=0x137a5e0, throwflag=<value optimized out>) at Python/ceval.c:1115
#11 0x00002b5b3b59fd26 in PyEval_EvalCodeEx (co=0x10a98a0, globals=<value optimized out>, locals=<value optimized out>, args=0x10bd118, argcount=4, kws=0x0, kwcount=0, 
    defs=0x0, defcount=0, closure=0x0) at Python/ceval.c:2831
#12 0x00002b5b3b547b2f in function_call (func=0x10b3758, arg=0x10bd100, kw=0x0) at Objects/funcobject.c:517
#13 0x00002b5b3b52b0e3 in PyObject_Call (func=0x149e640, arg=0x0, kw=0x2b5b3b856a10) at Objects/abstract.c:1860
#14 0x00002b5b3b5320bb in instancemethod_call (func=0x10b3758, arg=0x10bd100, kw=0x0) at Objects/classobject.c:2497
#15 0x00002b5b3b52b0e3 in PyObject_Call (func=0x149e640, arg=0x0, kw=0x2b5b3b856a10) at Objects/abstract.c:1860
#16 0x00002b5b3b59862d in PyEval_CallObjectWithKeywords (func=0x10fabe0, arg=0x10fa5a0, kw=0x0) at Python/ceval.c:3433
#17 0x00002b5b3cc69127 in pyg_closure_marshal (closure=0x17ded90, return_value=0x0, n_param_values=2, param_values=0x7fff6f7d65f0, invocation_hint=<value optimized out>, 
    marshal_data=<value optimized out>) at pygtype.c:1129
#18 0x00002b5b3cea5c9e in IA__g_closure_invoke (closure=0x17ded90, return_value=0x0, n_param_values=2, param_values=0x7fff6f7d65f0, invocation_hint=0x7fff6f7d64d0)
    at gclosure.c:490
#19 0x00002b5b3ceb9920 in signal_emit_unlocked_R (node=0xb29210, detail=671, instance=0x1411430, emission_return=0x0, instance_and_params=0x7fff6f7d65f0)
    at gsignal.c:2440
#20 0x00002b5b3cebb356 in IA__g_signal_emit_valist (instance=0x1411430, signal_id=<value optimized out>, detail=671, var_args=0x7fff6f7d6870) at gsignal.c:2199
#21 0x00002b5b3cebb743 in IA__g_signal_emit (instance=0x149e640, signal_id=0, detail=998599184) at gsignal.c:2243
#22 0x00002aaaad17c1e4 in gst_bus_async_signal_func (bus=0x1411430, message=0x148b6b0, data=<value optimized out>) at gstbus.c:981
#23 0x00002aaaad17cc8f in gst_bus_source_dispatch (source=0x149e230, callback=0x2aaaad17c180 <gst_bus_async_signal_func>, user_data=0x0) at gstbus.c:701
#24 0x00002b5b3d51bbd3 in IA__g_main_context_dispatch (context=0xa0b1a0) at gmain.c:2061
#25 0x00002b5b3d51eead in g_main_context_iterate (context=0xa0b1a0, block=1, dispatch=1, self=<value optimized out>) at gmain.c:2694
#26 0x00002b5b3d51f189 in IA__g_main_loop_run (loop=0x137a2d0) at gmain.c:2898
#27 0x00002b5b3dd89722 in IA__gtk_main () at gtkmain.c:1144
#28 0x00002b5b3d9435b2 in _wrap_gtk_main (self=<value optimized out>) at ./gtk.override:1134
#29 0x00002b5b3b59e125 in PyEval_EvalFrameEx (f=0xf4d1d0, throwflag=<value optimized out>) at Python/ceval.c:3548
#30 0x00002b5b3b59f37a in PyEval_EvalFrameEx (f=0xd1b5f0, throwflag=<value optimized out>) at Python/ceval.c:3650
#31 0x00002b5b3b59f37a in PyEval_EvalFrameEx (f=0x6689f0, throwflag=<value optimized out>) at Python/ceval.c:3650
#32 0x00002b5b3b59fd26 in PyEval_EvalCodeEx (co=0x2b5b3b374b70, globals=<value optimized out>, locals=<value optimized out>, args=0x0, argcount=0, kws=0x0, kwcount=0, 
    defs=0x0, defcount=0, closure=0x0) at Python/ceval.c:2831
#33 0x00002b5b3b59ffd2 in PyEval_EvalCode (co=0x149e640, globals=0x0, locals=0x2b5b3b856a10) at Python/ceval.c:494
#34 0x00002b5b3b5b9102 in run_mod (mod=<value optimized out>, filename=<value optimized out>, globals=0x6255d0, locals=0x6255d0, flags=<value optimized out>, 
    arena=<value optimized out>) at Python/pythonrun.c:1271
#35 0x00002b5b3b5b91d6 in PyRun_FileExFlags (fp=0x602010, filename=0x7fff6f7d816f "bin/pitivi", start=257, globals=0x6255d0, locals=0x6255d0, closeit=1, 
    flags=0x7fff6f7d74f0) at Python/pythonrun.c:1257
#36 0x00002b5b3b5ba65b in PyRun_SimpleFileExFlags (fp=0x602010, filename=0x7fff6f7d816f "bin/pitivi", closeit=1, flags=0x7fff6f7d74f0) at Python/pythonrun.c:877
#37 0x00002b5b3b5c31e4 in Py_Main (argc=<value optimized out>, argv=<value optimized out>) at Modules/main.c:523
#38 0x00002b5b3c105b74 in __libc_start_main (main=0x400780 <main>, argc=2, ubp_av=0x7fff6f7d7618, init=<value optimized out>, fini=<value optimized out>, 
    rtld_fini=<value optimized out>, stack_end=0x7fff6f7d7608) at libc-start.c:229
#39 0x00000000004006e9 in _start ()