SpigotMC/Spigot — pull request #90 by TheJeterLP (2014-01-04 16:24:28+00:00)
Title: Fix n must be positive

Sometimes this.getHighestBlockYAt(int, int) still returns 0.
We have to check first if it returns 0, and if its 0, set it to 256.
People will no longer get errors like this:
http://pastebin.com/G9CkQb4f