Crash when player in minecart is hitten upwards by a slimeblock

Can confirm. Attached crash report.

Minecraft Crash Report ----
// Don't be sad. I'll do better next time, I promise!

Time: 14/07/14 17:06
Description: Ticking entity

java.lang.IllegalArgumentException: Cannot get property bco{name=shape, clazz=class arw, values=[north_south, east_west, ascending_east, ascending_west, ascending_north, ascending_south, south_east, south_west, north_west, north_east]} as it does not exist in bby{block=minecraft:piston_extension, properties=[facing, type]}
at bcb.b(SourceFile:112)
at art.a(SourceFile:398)
at bbq.a(SourceFile:141)
at asa.a(SourceFile:526)
at apo.a(SourceFile:784)
at apo.a(SourceFile:660)
at xa.s(SourceFile:1544)
at aas.a(SourceFile:32)
at yf.a(SourceFile:20)
at yf.apply(SourceFile:17)
at com.google.common.base.Predicates$AndPredicate.apply(Predicates.java:359)
at bdb.a(SourceFile:766)
at apo.a(SourceFile:2217)
at ye.a(SourceFile:44)
at yr.a(SourceFile:75)
at xb.bD(SourceFile:458)
at xa.l(SourceFile:1431)
at xb.l(SourceFile:328)
at wd.l(SourceFile:126)
at xa.j(SourceFile:1299)
at xb.j(SourceFile:207)
at apo.a(SourceFile:1383)
at qi.a(SourceFile:572)
at apo.g(SourceFile:1361)
at apo.i(SourceFile:1255)
at qi.i(SourceFile:450)
at net.minecraft.server.MinecraftServer.x(SourceFile:586)
at net.minecraft.server.MinecraftServer.w(SourceFile:510)
at cui.w(SourceFile:132)
at net.minecraft.server.MinecraftServer.run(SourceFile:426)
at java.lang.Thread.run(Unknown Source)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at bcb.b(SourceFile:112)
at art.a(SourceFile:398)
at bbq.a(SourceFile:141)
at asa.a(SourceFile:526)
at apo.a(SourceFile:784)
at apo.a(SourceFile:660)
at xa.s(SourceFile:1544)
at aas.a(SourceFile:32)
at yf.a(SourceFile:20)
at yf.apply(SourceFile:17)
at com.google.common.base.Predicates$AndPredicate.apply(Predicates.java:359)
at bdb.a(SourceFile:766)
at apo.a(SourceFile:2217)
at ye.a(SourceFile:44)
at yr.a(SourceFile:75)
at xb.bD(SourceFile:458)
at xa.l(SourceFile:1431)
at xb.l(SourceFile:328)
at wd.l(SourceFile:126)
at xa.j(SourceFile:1299)
at xb.j(SourceFile:207)
at apo.a(SourceFile:1383)
at qi.a(SourceFile:572)
at apo.g(SourceFile:1361)

– Entity being ticked –
Details:
Entity Type: Villager (afs)
Entity ID: 1318884
Entity Name: Villager
Entity's Exact location: -357.70, 2.00, -355.08
Entity's Block location: -358.00,2.00,-356.00 - World: (-358,2,-356), Chunk: (at 10,0,12 in -23,-23; contains blocks -368,0,-368 to -353,255,-353), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Entity's Momentum: 0.00, -0.08, 0.00
Entity's Rider: ~_ERROR~ NullPointerException: null
Entity's Vehicle: ~_ERROR~ NullPointerException: null
Stacktrace:
at apo.i(SourceFile:1255)
at qi.i(SourceFile:450)

– Affected level –
Details:
Level name: New World
All players: 1 total; [ql['Echo23'/1318930, l='New World', x=-361.50, y=4.86, z=-363.49]]
Chunk stats: ServerChunkCache: 412 Drop: 0
Level seed: -3920607801628928692
Level generator: ID 01 - flat, ver 0. Features enabled: true
Level generator options:
Level spawn location: -310.00,4.00,-368.00 - World: (-310,4,-368), Chunk: (at 10,0,0 in -20,-23; contains blocks -320,0,-368 to -305,255,-353), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Level time: 101161 game time, 64756 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 56601 (now: false), thunder time: 13034 (now: true)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
at net.minecraft.server.MinecraftServer.x(SourceFile:586)
at net.minecraft.server.MinecraftServer.w(SourceFile:510)
at cui.w(SourceFile:132)
at net.minecraft.server.MinecraftServer.run(SourceFile:426)
at java.lang.Thread.run(Unknown Source)

– System Details –
Details:
Minecraft Version: 14w28b
Operating System: Windows 8 (amd64) version 6.2
Java Version: 1.8.0_05, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 1449893544 bytes (1382 MB) / 1641545728 bytes (1565 MB) up to 3817865216 bytes (3641 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4G
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Profiler Position: N/A (disabled)
Player Count: 1 / 8; [ql['Echo23'/1318930, l='New World', x=-361.50, y=4.86, z=-363.49]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

The issue is the rails and because of that, this duplicates MC-61795.
(Also, there is a button to attach files so you don't need to post the crash report in a comment.)