Segfault with graphic tracer

[nazar-pc]

I've just tried graphic tracer with master branch of gstreamer on my dynamic pipeline, but it segfaults more often than not.
Here is a backtrace:

Thread 117 "GstDotRender" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7efed2c88700 (LWP 32422)]
0x00007effdcefcf5b in _int_malloc (av=av@entry=0x7efecc000020, bytes=bytes@entry=16) at malloc.c:3608
3608    malloc.c: No such file or directory.
(gdb) bt
#0  0x00007effdcefcf5b in _int_malloc (av=av@entry=0x7efecc000020, bytes=bytes@entry=16) at malloc.c:3608
#1  0x00007effdceff449 in __GI___libc_malloc (bytes=16) at malloc.c:3066
#2  0x00007effdd11b4e9 in g_malloc () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007eff7e97cfb5 in  () at /lib/x86_64-linux-gnu/libpango-1.0.so.0
#4  0x00007eff7e97f092 in  () at /lib/x86_64-linux-gnu/libpango-1.0.so.0
#5  0x00007eff9f287c38 in  () at /usr/lib/x86_64-linux-gnu/graphviz/libgvplugin_pango.so.6
#6  0x00007effdc8542f9 in textspan_size () at /lib/x86_64-linux-gnu/libgvc.so.6
#7  0x00007effdc867abb in  () at /lib/x86_64-linux-gnu/libgvc.so.6
#8  0x00007effdc868548 in make_simple_label () at /lib/x86_64-linux-gnu/libgvc.so.6
#9  0x00007effdc8686a0 in make_label () at /lib/x86_64-linux-gnu/libgvc.so.6
#10 0x00007effdc85d8f0 in do_graph_label () at /lib/x86_64-linux-gnu/libgvc.so.6
#11 0x00007eff7e05d92e in  () at /usr/lib/x86_64-linux-gnu/graphviz/libgvplugin_dot_layout.so.6
#12 0x00007eff7e05fbfa in  () at /usr/lib/x86_64-linux-gnu/graphviz/libgvplugin_dot_layout.so.6
#13 0x00007eff7e05e7f3 in  () at /usr/lib/x86_64-linux-gnu/graphviz/libgvplugin_dot_layout.so.6
#14 0x00007eff7e05e849 in  () at /usr/lib/x86_64-linux-gnu/graphviz/libgvplugin_dot_layout.so.6
#15 0x00007eff7e05fb9d in dot_rank () at /usr/lib/x86_64-linux-gnu/graphviz/libgvplugin_dot_layout.so.6
#16 0x00007eff7e0552a0 in  () at /usr/lib/x86_64-linux-gnu/graphviz/libgvplugin_dot_layout.so.6
#17 0x00007eff7e055aa8 in dot_layout () at /usr/lib/x86_64-linux-gnu/graphviz/libgvplugin_dot_layout.so.6
#18 0x00007effdc83ef0b in gvLayoutJobs () at /lib/x86_64-linux-gnu/libgvc.so.6
#19 0x00007effdc845dfa in gvLayout () at /lib/x86_64-linux-gnu/libgvc.so.6
#20 0x00007effdc8bddf8 in gst_dot_x11_render (dot_string=<optimized out>, args=<optimized out>) at gstdot.c:176
#21 0x00007effdc8bda01 in gst_dot_render_thread (data=0x7efefc01dc90) at gstdot.c:134
#22 0x00007effdd13f111 in  () at /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007effdd076669 in start_thread (arg=<optimized out>) at pthread_create.c:479
#24 0x00007effdcf84323 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Any idea why this can be?