Unfortunately, svn does not include any sort of information on when a file moves/is renamed in their diffs. There's no metadata we can rely upon. We'd have to basically add a bunch of smarts to augment the format of the diff to contain that information, but it's not on the immediate to-do list.
Git handles this pretty well. Subversion has a --git option to svn diff that one would hope would really have that information, and it *sort of* does, but it'd require a lot of changes to support, and won't work today.