Why is python 3.6.1. not available in pyenv?

If you installed pyenv via pyenv installer:

pyenv update

If you installed pyenv via Homebrew

brew upgrade pyenv

If you installed pyenv via Git:

cd $(pyenv root) && git pull

I tried pyenv update but that did not resolve the issue for me.

I had to brew update && brew upgrade pyenv before doing pyenv install 3.6.1