What we did:

• Updated server from minecraft_server.14w08a.jar to minecraft_server.14w10b.jar
• Logged in to server with 14w10b client

What happen:

• Played spawned at original spawn location
• Players inventory was cleared (empty)
• Players ender chests was cleared (empty)

Is likely related to the UUID update. It appears world data for the player is not preserved or not migrated