kernel-mod_checkzlibinflate_configured calls kernel-mod_badconfig_zlib, but it is not defined anywhere. If this is supposed to be defined by the ebuild itself, then it's not documented anywhere I can find. To simulate: 1) create an ebuild that inherits kernel-mod 2) call kernel-mod_checkzlibinflate_configured 3) notice the error message
ebuild/eclass bugs go to the ebuild/eclass maintainer, not portage devs- we just maintain portage, the software.
kernel-mod is going away, linux-mod and linux-info are the successors. This issue does not appear to exist there. Thanks for reporting.