Invoking alohaBlock() and then mahaloBlock() on a node leaves junk behind on the node, namely class="aloha-block-DefaultBlock" contenteditable="false" data-aloha-block-type="DefaultBlock" as well as an autogenerated id.
This material should be cleaned up during mahaloBlock() since it can mess up tools that use the results.
This is related to issue 459, which notes that aloha()/mahalo() has similar problems.
Related to aloha/ephemera?
I think mahaloBlock should clean the ephemera content of a specific block instance, and Ephemera.prune should clean all blocks.