robbyrussell/oh-my-zsh — pull request #3049 by strycore (2014-08-21 10:51:14+00:00)
Title: Prevent chsh from running when $SHELL is already zsh

The chsh command in the install script will prompt the user for a password, which is inconvenient for automated installs of Oh My ZSH.
By setting the default shell before running the install script and running the chsh conditionaly, this allows for fully automated OhmyZSH installs.