Tnt activated go through the fence when there is a block above the tnt block(without the block above the tnt did not bug).
I played before in 1.8.2 pre 1 and this bug wasn't here.
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Regression of MC-12730

not exactly the same bug, you need a block above the tnt for have this bug, if there is nothing above the tnt stay in the good place. I think its because the tnt became an entity and she have just an half block to stay (1.5 block the fence and the block above no let to the tnt the space she need) so she pass through the fence.

MC-12730 is back in 15w47c.