When trying to merge it tries to download the package from a mirror. This is bc the debian mirror does not have the file anymore. Kinda like bug id 820923.
Please attach the build.log. This packages is mirrored on gentoo mirrors, it should work. Most probably you have a broken mirror in your GENTOO_MIRRORS.
Currently my gentoo system is prety broken so ill try to answer you when i get it fixed
Yeah just my mirrors are broken