trac-webadmin has been integrated into the core package of trac-0.11. May be block or a warning should inform users trying to update trac to 0.11* and having trac-webadmin installed and/or for users trying to install trac-webadmin and having trac 0.11* installed ? (see URL for more informations)
Oups, I didn't see =www-apps/trac-0.10* Sorry...