This is a bug that only happens in Tesseract / OctaForge (maybe affects other
engines that I didn't test), but when I set a block's face to sky tex, my whole
system hangs for about 15 seconds, then the screen goes to black, powers off,
powers back on and the display is back, until it hangs entirely (the screen
doesn't go blank this time). Using ATI Mobility Radeon HD5470 on an Acer Aspire
5742G-7353, OpenSUSE Tumbleweed. I couldn't get a backtrace due to my system
being unrecoverable after the event. REISUB works, obviously.