Resubmit should generate interdiffs

[Aaron Bentley]

When resubmit is used, we should generate an interdiff. It should be attached to the initial email, and it should be shown in the page. It should show only changes originated in the branch, not changes that were merged in.

[Robert Collins (lifeless)]

I'm not clear what would be interdiffed here. Also is it meaningfully different to the use of your clever diff plugin on incremental commits?

[Aaron Bentley (abentley)]

By "Interdiff", I meant a diff showing only the changes made on the mainline after the review, so that it is easy for the reviewer to see what changes were made to address their review.

A "bzr diff -r $REVIEWED_REV..-1" would suit the purpose except that it would also include changes merged in from the target branch.

This is somewhat addressed by the post-comment revision diffs we now include, but those will show merges from the target. They also take a long time to appear, once requested.

[Aaron Bentley (abentley)]

And they aren't put into emails at all.