Minecarts with tnt don't explode when getting off unpowered powered-rails or acrivator-rails

Problem:
When i push a minecart whith tnt off of a unpowered powered-rail it doesn't explode.

Additional comment:
I dont know if that's what it's supposed to do, but when pushing it off a normal rail it explodes. So i don't see the logic.

How to reproduce:
push a minecart off an unpowered powered-rail