When a minecart usually stops on a Powered Rail that is not currently powered. If the minecart contains a villager then the cart sometimes continues as if the rail is powered. If this rail ends at a block then the minecart changes direction. Only (thus far) reproduced when picking up villagers from an area with water in it.

What I expected to happen was:
The minecart stops.

What happened:
The minecart continued moving,

Steps to recreate:
1. Create a villager pen with water streams.
2. Place normal rails between pen and two stacked blocks with a powered rail in the middle and one at each end.
3. Power the rails in the middle and on the side where the pen is.
4. Place a button on the top block on the other side.
5. Place a cart on the side opposite to the pen.
6. Spawn villagers in the pen
7. Press the button to pick up a villager.