As explained in parent bug Thanks!
09 Jun 2015; Manuel Rüger <mrueg@gentoo.org> activerecord-3.2.21.ebuild, activerecord-4.0.13.ebuild, activerecord-4.1.10.ebuild, activerecord-4.2.1.ebuild: Rename sqlite3 USEflag to sqlite. Fixes bug #548654.