I put a bunch of tnt-minecarts on a piece of normal rails, let them drive over an activator rail. after this I let them drive over a bunch of unpowered rails (which didn't stop the minecarts). also none of the rails or the underlying blocks blew up

What I expected to happen was...:
the activated TNT minecarts would stop on the unpowered powered rails, and would blow up everything around them

What actually happened was...:
the minecarts didn't stop, and the rails and the blocks under the rails didn't blow up

Steps to Reproduce:
1. place an activator rail
2. connect some powered rails to to the activator rail
3. make a closed circuit using powered rails for straight bits, and normal rails for corners
4. put a bunch of tnt-minecarts on the rails
5. activate the activator rail
6. push the minecarts over the activator rail
7. enjoy