Complex Piston Mechanisms Cause Crash

When using the snapshot on my server, my somewhat complex hidden piston staircase caused a server crash every time it was used. Here is a snippet from the log:

2:43:27 PM PDT CONSOLE: thread/ERROR]: Can't setBlockAndData(minecraft:piston_extension, 6) as it's an invalid block state. Defaulting to minecraft:piston_extension[facing=down,type=default] instead (data 0)
2:43:27 PM PDT CONSOLE: set property ayl

{name=facing, clazz=class dt, values=[down, up, north, south, west, east]}

to null on block minecraft:piston_extension, it is not an allowed value
2:43:28 PM PDT CONSOLE: Source) [?:1.7.0]
2:43:28 PM PDT Server: Server is restarting. World is being saved.