gnustep-libs/cenonlibrary-3.83 no longer works as the package no longer exists at the address http://ftp.fi.muni.cz/pub/linux/gentoo/distfiles/CenonLibrary-3.83-1.tar.bz2
Do you use an overlay? 3.83 was never in official tree: http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/gnustep-libs/cenonlibrary/?hideattic=0 so the Gentoo mirrors do not have the source file (they still have 3.82 as this version is still in tree) Also current stable is 3.9.4, do you need this specific older version?
Sorry, my bad, must have added the overlay and forgotten about it! I've upgraded to 4.0.2 as it was in testing but found whilst it installed ok it doesn't work very well. I'll switch to 3.9.5 which seems to be current stable version (well if you can call Cenon stable)! I'll close this bug as the ebuild is deprecated. Thanks anyway.