TNT destruction nerfed

All explosions seem nerfed but the main thing is TNT blows up less then in any full resleases which I believe this to be a bug as it is not in the change log.

What I expected to happen was...:
I expected to have all the stone I place blown up.

What actually happened was...:
It left the bottom corner blocks.

Steps to Reproduce:
1. Make a 3 by 3 by 3 thing of stone or cobblestone.
2. Next replace the center block of the 3 by 3 section in the middle with TNT and then light it
3. Then what should be left if done in 14w11b are 4 blocks from the bottom layer were there should be none if done in 1.7 and version before.