É think there is not such tool to do what you want

On Mon, Nov 3, 2008 at 2:17 PM, Momesso Andrea <momesso.andrea@gmail.com> wrote:
Is there a way to to update svn packages only when there are updates in
the svn source?

Actually I use a script to grep "9999" from eix -I output and put all
those packages in a package set, then I have a cron job to rebuild this
set weekly.

What I'd like to do is to only fetch the svn sources, and rebuild the
packages if sources have been updated since last build, saving lots of
compilations.

Does portage (or any other tool) provide a way to do it?