Comment 2 for bug 1218839

StacktraceTop:
 compute_image_info (image=0x7f802fa79ab0) at ../../pixman/pixman-image.c:282
 _pixman_image_validate (image=image@entry=0x7f802fa79ab0) at ../../pixman/pixman-image.c:539
 pixman_image_composite32 (op=PIXMAN_OP_SRC, src=0x7f802fa79ab0, mask=0x0, dest=0x7f802f94d7e0, src_x=0, src_y=169, mask_x=24576, mask_y=-32727, dest_x=0, dest_y=169, width=600, height=169) at ../../pixman/pixman.c:592
 pixman_image_composite (op=<optimized out>, src=<optimized out>, mask=<optimized out>, dest=<optimized out>, src_x=<optimized out>, src_y=<optimized out>, mask_x=<optimized out>, mask_y=<optimized out>, dest_x=<optimized out>, dest_y=<optimized out>, width=<optimized out>, height=<optimized out>) at ../../pixman/pixman.c:730
 thread_composite (arg=arg@entry=0x7fff04649f10) at ../../../src/sna/sna_threads.c:232