All blocks and items in a container in a map gets deleted (even blocks in inventory) when switching from 14w03b to Minecraft 1.7.
Containers include:
Dispensers
Item Frames
Inventory
Minecart with Chest
Chest
Hoppers
Droppers
and probably other containers.
Related issues
duplicates
Comments
galaxy_2alex
migrated
Duplicate of Invalid
MC-45009
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