Comment 5 for bug 813349

OK, in <https://code.qastaging.launchpad.net/~mbp/bzr/doc-2.4/+merge/65290> I can see the diff appearing on the incremental revisions.

We ought to also add this feature on the initial mp revisions, and on the branch itself, but that can be done separately.

Also this makes it stick out to me how weirdly different the inital mp revisions are from those added after it's created.