I can not confirm that this happens now, but that was also the case for 1.7 (see above comments).
Tested, did not seem to occur in 1.7.4 with the same world, although I can not fully confirm that.
I am not sure if this still affects the game, but I'll test it out when I have time to.
-7344306588808213900
It's happening in any coordinates around x: 20, z: 87, and (I think) only when generating new chunks.
I'll have to say I have no idea. Haven't got it in any world after the initial one; I have played both release and snapshot versions lately. I even tried to recreate the scenario I had that time, no luck.