dev-python/httplib2 uses an own bundled CA Store, this should be unbundled similar to what is being done by debian https://sources.debian.net/src/python-httplib2/0.9.2%2Bdfsg-1/debian/patches/use_system_cacerts.patch/ the patch can be used verbatim, with /etc/ssl/certs/ca-certificates.crt being provided by app-misc/ca-certificates. This enhances both security, by providing one CA store to maintain properly, and usability (the separate CA store was detected due to issue in bug 624450)
PR: https://github.com/gentoo/gentoo/pull/5092
Fixed via https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=4ebc6fc6c47249c50409be161e37d5584ee51c87
Re-opening as it isn't yet in stable
httplib2-0.10.3-r1 is now the oldest version in tree and is stable.