Comment 2 for bug 187711

Aaron, do you think that a PreviewTree will work as the target branch for a merge?

Because if it does, I think you can make this work by making a preview tree, let's call it P1, of the merge of the dependent branch into the target branch, then making another preview tree, P2, by merging the source branch into P1, then displaying the diff between P1 and P2. But I'd like to know if this approach has any hope before I starting trying things...