On a python 3.6 system Electrum won't build, requiring python 3.4 or 3.5 to be installed. The electrum developers make no mention, as far as I can see, of their program not working on python 3.6 Reproducible: Always The problem is very easy to fix, just by changing the ebuild line PYTHON_COMPAT=( python3_{4,5} ) to PYTHON_COMPAT=( python3_{4,5,6} ) as I've already done on my local ebuild.
It was reverted back in commit https://github.com/gentoo/gentoo/commit/e064788e4abe261de453d91e2c54c090a8f6f07e
please try electrum-3.1.1