Ride a horse and You'll be trapped FOREVER

After a few tests I can to the Problem with Horses in the 1.8 Spigot/craftbukkit and Single Player Versions.
This Bug never Happened before just now.
The Bug:
If you Tame or Ride a horse, you can't leave it.You are Trapped there. Even Disconnecting doesn't help.
I don't know wich Versions are also Attacked from this bug only 1.8