Needless to say that jpeg-9c is not in tree yet and jpeg-9 seems to be hopeless anyway (see bug 479818).
Not sure of the best solution yet.
The bug has been referenced in the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=f25169de9a9af59ecfa9172dbaaee33ca155e316 commit f25169de9a9af59ecfa9172dbaaee33ca155e316 Author: Andreas Sturmlechner <asturm@gentoo.org> AuthorDate: 2018-02-01 23:17:26 +0000 Commit: Andreas Sturmlechner <asturm@gentoo.org> CommitDate: 2018-02-03 00:29:05 +0000 media-libs/jpeg: 9c version bump Bug: https://bugs.gentoo.org/646366 Package-Manager: Portage-2.3.22, Repoman-2.3.6 media-libs/jpeg/Manifest | 1 + media-libs/jpeg/jpeg-9c.ebuild | 71 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 72 insertions(+)}
*** Bug 646930 has been marked as a duplicate of this bug. ***
Considering this fixed jpeg-9c is now stable on all relevant arches.