Any horse tamed in 13w19a cannot be controlled even though there is a saddle on it. But the horse can be made to jump, they also lose their saddles when upgrading to 13w21a.
Steps to reproduce:
1. Load snapshot 13w19a and spawn a horse, and saddle it.
2. Close Minecraft, and load snapshot 13w21a and load the world.
3. Add a saddle to that horse, and try to ride it.
4. The horse can be forced to jump, but cannot be forced to move.