Comment 2 for bug 1506916

StacktraceTop:
 is_clipped (d=0x0, d=0x0, r=0x50) at ../../../src/sna/sna.h:1240
 __sna_dri2_copy_region (sna=0x7f3ceb60f000, draw=0x0, region=0x11, src=0x55fa21fe0760, dst=0x7ffd9fc7e980, flags=4) at ../../../src/sna/sna_dri2.c:1156
 sna_dri2_immediate_blit (sync=false, info=<optimized out>, sna=0x55fa21ff7280) at ../../../src/sna/sna_dri2.c:2684
 sna_dri2_schedule_swap (client=<optimized out>, draw=<optimized out>, front=0x55fa21ff5cd0, back=<optimized out>, target_msc=0x7ffd9fc7eb38, divisor=<optimized out>, remainder=0, func=0x55fa1fe25ca0 <DRI2SwapEvent>, data=0x55fa21fa6c20) at ../../../src/sna/sna_dri2.c:3288
 DRI2SwapBuffers (client=client@entry=0x55fa21fcd4c0, pDraw=0x55fa21fa6c20, target_msc=9144, divisor=0, remainder=<optimized out>, swap_target=swap_target@entry=0x7ffd9fc7ebd8, func=0x55fa1fe25ca0 <DRI2SwapEvent>, data=0x55fa21fa6c20) at ../../../../hw/xfree86/dri2/dri2.c:1163