See $summary. Current ebuild looks like this: PYTHON_COMPAT=( python2_7 python3_{4,5,6} pypy ) inherit distutils-r1 ... DEPEND="dev-python/setuptools" RDEPEND="${DEPEND} >=dev-python/appdirs-1.4.0 >=dev-python/cached-property-1.3.0 >=dev-python/defusedxml-0.4.1 >=dev-python/isodate-0.5.4 >=dev-python/lxml-3.0.0 >=dev-python/requests-2.7.0 >=dev-python/requests-toolbelt-0.7.1 >=dev-python/six-1.9.0 dev-python/pytz async? ( >=dev-python/aiohttp-1.0 ) tornado? ( >=www-servers/tornado-4.0.2 )"
Fixed by https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=545b3819819f93b4d8bdaffa3773b0d6c4353c41