That report states that a render distance above 12 causes the issue; I always use a render distance of 6 though. is this simply a cpu/gpu performance problem?
I'm not quite sure what it is either. When I got up close to the affected area, the glitchy texture seemed to be composed of the item texture list, similar to what you see with the notenoughitems mod or the creative inventory
I am using a texture pack in the screenshots, however the issue was still present while using the default as well.
Definitely not an urgent issue, I don't see this ever being a real problem for anybody, just thought maybe preventing people from /filling blocks in invalid locations, such as how trapdoors work, may be a good solution.