This is one of the four packages still requiring the ancient: ~dev-python/mock-1.0.1[${PYTHON_USEDEP}] That said, the project died back in 2013 and the modern is replacement is social-app-django which we don't package. I'd say treeclean it.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=5fc634d7198fc7ba8961370024f03b7c5619364a commit 5fc634d7198fc7ba8961370024f03b7c5619364a Author: Mikle Kolyada <zlogene@gentoo.org> AuthorDate: 2018-04-21 14:50:31 +0000 Commit: Mikle Kolyada <zlogene@gentoo.org> CommitDate: 2018-04-21 14:51:39 +0000 dev-python/django-social-auth: remove last rited package Closes: https://bugs.gentoo.org/643506 dev-python/django-social-auth/Manifest | 1 - .../django-social-auth-0.7.28.ebuild | 43 ---------------------- dev-python/django-social-auth/metadata.xml | 11 ------ 3 files changed, 55 deletions(-)