What happen when installing oh-my-zsh configuration without having zsh installed ( => should add a check if shell is installed )

ohmyzsh

root@precise32:~# curl -L http://install.ohmyz.sh | sh
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   104  100   104    0     0    159      0 --:--:-- --:--:-- --:--:--   650
  0     0    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0
100  1779  100  1779    0     0   1119      0  0:00:01  0:00:01 --:--:-- 42357
Cloning Oh My Zsh...
Cloning into '/root/.oh-my-zsh'...
remote: Reusing existing pack: 10071, done.
Receiving objects: 100% (10071/10071), 2.04 MiB | 500 KiB/s, done.
remote: Total 10071 (delta 0), reused 0 (delta 0)
Resolving deltas: 100% (5169/5169), done.
Looking for an existing zsh config...
Using the Oh My Zsh template file and adding it to ~/.zshrc
Copying your current PATH and adding it to the end of ~/.zshrc for you.
Time to change your default shell to zsh!
chsh: option requires an argument -- 's'
Usage: chsh [options] [LOGIN]

Options:
  -h, --help                    display this help message and exit
  -s, --shell SHELL             new login shell for the user account

root@precise32:~#