Gentoo's Bugzilla –
Attachment 369188 Details for
Bug 464104sys-apps/portage-2.2.0_alpha169: sys-libs/glibc-2.17 upgrade - /usr/bin/python2.7: relocation error: /lib64/libresolv.so.2: symbol __sendmmsg, version GLIBC_PRIVATE not defined in file libc.so.6 with link time reference