Good evening !
I'm an administrator of a french server, and I tried the 1.7.2 on a debug serveur.
Previously, I've paste a schematic from a 1.6.4 world on a 1.7.2 world, using MCEdit. I've visited the pasted buildings on my server, but "internal serveur error" appears when I approach some buildings.

Here is the error we can see on the console :

[17:36:26] [Server thread/WARN]: Failed to handle packet for /My_IP
java.lang.RuntimeException: Already decorating!!
at agm.a(SourceFile:21) ~[minecraft_server.jar:?]
at agg.a(SourceFile:362) ~[minecraft_server.jar:?]
at ahb.a(SourceFile:74) ~[minecraft_server.jar:?]
at apl.a(SourceFile:432) ~[minecraft_server.jar:?]
at mi.a(SourceFile:160) ~[minecraft_server.jar:?]
at aoj.a(SourceFile:781) ~[minecraft_server.jar:?]
at mi.c(SourceFile:95) ~[minecraft_server.jar:?]
at mh.<init>(SourceFile:31) ~[minecraft_server.jar:?]
at mg.a(SourceFile:212) ~[minecraft_server.jar:?]
at mg.d(SourceFile:346) ~[minecraft_server.jar:?]
at ld.d(SourceFile:215) ~[minecraft_server.jar:?]
at mx.a(SourceFile:280) ~[minecraft_server.jar:?]
at ir.a(SourceFile:137) ~[minecraft_server.jar:?]
at it.a(SourceFile:20) ~[minecraft_server.jar:?]
at ef.a(SourceFile:164) ~[minecraft_server.jar:?]
at ms.c(SourceFile:134) [minecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.u(SourceFile:529) [minecraft_server.jar:?]
at lj.u(SourceFile:265) [minecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.t(SourceFile:441) [minecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:358) [minecraft_server.jar:?]
at ky.run(SourceFile:617) [minecraft_server.jar:?]
[17:36:26] [Server thread/INFO]: Almathy lost connection: TextComponent{text='Internal server error', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null}}
[17:36:26] [Server thread/INFO]: Almathy left the game

I don't know if other people have the same problem, so I prefer report the bug.

I hope that my report will be useful,
Sincerely, Almaty

PS: Sorry for my no perfect english