When trying to emerge docker-compose in its current version I do get a “no ebuilds to satisfy” message:

emerge: there are no ebuilds to satisfy ">=dev-python/docker-py-2.5.1[python_targets_python2_7(-)?,python_targets_python3_4(-)?,python_targets_python3_5(-)?,python_targets_python3_6(-)?,-python_single_target_python2_7(-),-python_single_target_python3_4(-),-python_single_target_python3_5(-),-python_single_target_python3_6(-)]".
{{ (dependency required by "app-emulation/docker-compose-1.16.1::nokit" [ebuild]) }}
{{ (dependency required by "docker-compose" [argument]) }}

 Perhaps related, I'm also using python-kit/3.4-prime.