Comment 2 for bug 1383449

StacktraceTop:
 _tor_blt_src (in=0x7fff0d3d6bd0, box=<optimized out>, v=16 '\020') at ../../../src/sna/sna_trapezoids_imprecise.c:2197
 tor_blt (unbounded=1, height=<optimized out>, y=<optimized out>, span=0x7f5a1fb67350 <tor_blt_src>, clip=0x7f5a278e79e0, op=0x7fff0d3d6bd0, converter=0x7f5a1f2aa300, sna=0x0) at ../../../src/sna/sna_trapezoids_imprecise.c:1127
 tor_render (sna=sna@entry=0x0, converter=converter@entry=0x7f5a1f2aa300, op=op@entry=0x7fff0d3d6bd0, clip=0x7f5a278e79e0, span=0x7f5a1fb67350 <tor_blt_src>, unbounded=1) at ../../../src/sna/sna_trapezoids_imprecise.c:1230
 inplace_thread (arg=0x7fff0d3d6bb8) at ../../../src/sna/sna_trapezoids_imprecise.c:2898
 __run__ (arg=0x7f5a269fe0e0) at ../../../src/sna/sna_threads.c:65