sk89q/worldedit — pull request #290 by ArchmageInc (2014-02-04 15:26:58+00:00)
Title: Added Water and Lava to BlockType place last queue.

Water and Lava (flowing liquids) can flow when pasting incrementally. This can cause unintended inconsistent pastes. This decision was based on the same reason to have Anvil in the place last queue.