The sparc keyword was removed on this new version of amavisd-new due to new app-arch/freeze dependency not keyworded on sparc yet. Please keyword app-arch/freeze on sparc, and then add back the sparc keyword to amavisd-new-20040701. Please do not mark amavisd-new-20040701 stable yet, as I'd like it to go through some testing. Thank you Ciaran for pointing out this dependency issue which repoman did not find. Thanks!
Sorry for taking so long for getting to this. Added ~sparc keyword to both freeze and amavisd-new. Thanks for the bug report.