Due to recent enhancements of binary packages support it is required to set the lowest EAPI to 4. Please migrate to higher EAPI or drop versions with old EAPIs until 30 September 2013.
Looks like all versions in the tree are eapi3 :|
05 May 2015; Justin Lecher <jlec@gentoo.org> -ccp4-apps-6.1.3-r11.ebuild, -ccp4-apps-6.1.3-r12.ebuild, ccp4-apps-6.1.3-r13.ebuild: Drop old