Losing connection to server when a Minecart Command Block is placed on a powered Activator Rail

Losing connection to server when a Minecart Command Block is placed on a powered Activator Rail.

What I expected to happen was...:
That the players would not lose connection to the server

What actually happened was...:
As soon as the Minecart Command Block was on the powered Activator Rail everyone loses connection to the server. (If a local server the host does not loose connection).

Steps to Reproduce:
1. Run Minecraft as a server
2. Have multiple people on server
3. Place Minecart Detector Rail on Activator Rail
4. Power Activator Rail
(Note: Steps 3 and 4 are interchangeable)
5. Client Crashes

Error: Internal exception: Java.io.IOException: received string length longer than maximum allowed (88>64)