Win10: MINGW64: install zsh & git

// update
$ pacman -Syu

// install zsh & git
$ pacman -S zsh git

$ git --version
git version 2.19.2

$ zsh --version
zsh 5.6.2 (x86_64-pc-msys)

// install oh-my-zsh
$ sh -c "$(curl -fsSL https://raw.github.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"
or
$ sh -c "$(wget https://raw.github.com/robbyrussell/oh-my-zsh/master/tools/install.sh -O -)"