* Inventory serialisation no longer double-sha's the content. (Robert Collins)
* XML inventory serialisation takes 20% less time while being stricter about the contents. (Robert Collins)
* Tree's with bad state such as files with no length or sha will no longer be silently accepted by the repository XML serialiser. To serialise inventories without such data, pass working=True to write_inventory. (Robert Collins)
* New method on xml serialisers, write_inventory_to_lines, which matches the API used by knits for adding content. (Robert Collins)