/up breaks blocks that already exist

[Riot]

Originally posted by dl69: "a player that has access to this command can simply type /up 0 to break the piece of bedrock that is below their feet." http://code.minecraftonline.com/scripts/issue/16/up-can-be-used-to-break-bedrock

In fact this shouldn't happen with any block.

[Blobehh]

Didnt see this untill after I found the bug, when on top of a chest and doing /up 1 it will delete the chest and throw its contents all over the floor. EDIT: While /up 0 will put the glass block below the chest when on top of the chest.

[Tyler Waugh]

There needs to be an additional check in LocalPlayer.ascendUpwards to check for a block at the players feet. Can't do it until at least Saturday personally.

[Anna Bakker]

With the chest bit, it's probably because it thinks you are where the chest is, as it isn't quite a full block. So standing on a chest would be the same as if you were standing where the chest is. This would also happen if you were standing in tall grass or on a slab and used /up 1.

[Jason Jones]

https://bitbucket.org/minecraftonline/worldedit/commits/ea60dda1094856909b7c3330cee27a71ccbf6e1c