Destroying a wall empties the wood stockpile.

For example, I'm trying to destroy this wall:
http://i.imgur.com/w3clU.png

Notice that It uses only 4 wood. When is destroyed, some wood from my wood stockpil is autoteleported to the destroyed zone. Now there are 10 woods in the destroyed area instead of only four.
http://i.imgur.com/LnDZc.png

UPDATED: Wood hauling deactivated. In order to test the bug, just unbuild the tower-cap wall.

http://i.imgur.com/GwjM8.png