Acrobot/CraftBukkitFork — pull request #2 by Acrobot (2012-06-14 14:50:36+00:00)
Title: Fix add/removeItem from CraftItemStack, so it doesn't modify the arguments [Fixes BUKKIT-1803]

The original ItemStack was being changed, so it could cause problems with plugins, which use the original ItemStack later.

Associated JIRA ticket:
https://bukkit.atlassian.net/browse/BUKKIT-1803