Comment 33 for bug 81689

> This sounds a bit like you're planning to do it command-by-command.
> It doesn't belong in the command layer; it should be somewhere near
> the tree.
>

The main changes at the moment are in transform.py and delta.py,
though some changes are present in commit.py and diff.py.
I will go ahead and make the merge proposal so that I can improve the
patch based on review comments.