dev-python/botocore-1.12.0 has been released[1], including Python 3.7 support. Technically it's a 0-day version bump, but the latest version in tree is 1.10.35, so I suspect botocore is sorta forgotten =\ [1]: https://github.com/boto/botocore/commit/2acf6a4f64e8cfeb7c22a50f663b43019b6452f8
does the -9999 work flawless on your system?
Yeah, sorry, I was behind the schedule with maintenance of my packages. Tested the updates last night, pushed the bumps a minute ago. No python 3.7 yet, I sent a patch to dev-python/jmespath (a dependency of botocore) to aballier (maintainer of it) just last night. Will keep this ticket posted when Python 3.7 support lands.
Just pushed botocore and boto3 updates with python3_7 available. Unstable now of course. Will request stabilization in a month. Hope this works for you. Closing for now. Thanks for computing with Gentoo Linux!