Patchdiff

Heya,

Do we have anything that allows me to compare two versions of a patch? In theory it'd do something like "apply both patches to the their merge base, then show the diff between the results". I don't think we have something like that, since there's probably some major caveats about conflicts when applying the patches to their merge-base. Or perhaps my theory is silly, and there's an easier way to compare two patches (other than looking at a diff's diff, which I've never been good at).