All versions <3.9 are masked
/var/git/meta-repo/kits/core-kit/profiles/package.mask/00-gentoo:

1. Andreas K. Hüttel <dilfridge@gentoo.org> (04 Nov 2017)
2. Many, many, many open bugs. Blocks gcc-6 stabilization.
3. Removal of the old versions in 30 days; please upgrade to
4. Audacious 3.9 (may require manual keywording since not
5. marked stable anymore).
   Reference: https://forums.funtoo.org/topic/1389-is-there-command-to-do-what-it-needs/#comment-6781