[MC-103981] Missing BlockEntity (Piston

Note from the moderators

This ticket is for crashes on vanilla clients and servers only.

As a workaround, you can play on 1.10 for now: Start the launcher, select Edit Profile. In the Use Version dropdown menu, select release 1.10. Then click Save Profile.

Description: Server forgot to send required information to construct BlockEntity

java.lang.RuntimeException: Missing BlockEntity
	at bqy.b(SourceFile:162)
	at bqu.a(SourceFile:100)
	at bqu.run(SourceFile:43)
	at java.lang.Thread.run(Thread.java:745)

http://hopper.minecraft.net/crashes/minecraft/MCX-2840146/

Ways to reproduce:

Confirmed: Piston extensions, for example placed on their own for decoration using /setblock ~ ~ ~ piston_extension
Confirmed: Flower pots placed in worlds created in 1.6.4 or older, even if the world has been opened in versions > 1.6.4 (~~MC-103992~~)
Unconfirmed: Command blocks, world download sent to [Mojang] Searge (Michael Stoyke) according to ~~MC-104216~~

Missing BlockEntity (Piston_Extension, ...)

Ways to reproduce: