Using Advanced turtle with pickaxe excavating a 2x2 landform, i dropped a creeper in, when it hit it it froze and crashed
Crash report: http://pastebin.com/N9WVcev8

I can duplicate this. It seems like when the creeper gets inside of the turtle and falls down a block and starts sufficating it crashes.

I think this is related issue. Happen to me when turtle moved (or attacked/tried to suck not sure) into my player on head level. http://pastebin.com/KL0WQg0L
EDIT: Fixed paste link.

Fixed for 1.76pr1, thanks!