Comment 2 for bug 953502

StacktraceTop:
 __assert_fail_base (fmt=0xb4f11698 <Address 0xb4f11698 out of bounds>, assertion=0xb638d8a9 "! surface->finished", file=0xb638d640 "/build/buildd/cairo-1.10.2/src/cairo-surface.c", line=385, function=0xb638dae0 "_cairo_surface_begin_modification") at assert.c:94
 __GI___assert_fail (assertion=0xb638d8a9 "! surface->finished", file=0xb638d640 "/build/buildd/cairo-1.10.2/src/cairo-surface.c", line=385, function=0xb638dae0 "_cairo_surface_begin_modification") at assert.c:103
 _cairo_surface_begin_modification (surface=0x9a6bdd8) at /build/buildd/cairo-1.10.2/src/cairo-surface.c:385
 _cairo_surface_paint (clip=0xbffcd278, source=0xbffcd198, op=<optimized out>, surface=0x9a6bdd8) at /build/buildd/cairo-1.10.2/src/cairo-surface.c:2019
 _cairo_surface_paint (surface=0x9a6bdd8, op=CAIRO_OPERATOR_OVER, source=0xbffcd198, clip=0xbffcd278) at /build/buildd/cairo-1.10.2/src/cairo-surface.c:1993