Strange TNT behaviour with example TNT cannons

The bug is about TNT being a "bit" messed up (differing from the PC edition), making it so that for example if you make a TNT cannon with 2 or more layers of TNT dropping down to the chamber, and then when the TNT is ignited and it blows up it destroys blocks like "normal" (even when submerged in water!) Affects at least v. 0.13.0 build 5