Thing is that the shell there is bash but all utilities (like unzip etc) are based on busybox (
http://www.busybox.net/).
This means that not all options are available.
Also, the $OS variable looks like to give Windows_NT, which then leads to the "Unsupported OS" message (for the VM for example).
What is the environment you guys do use for testing those scripts on Windows (Windows 7 in my case)?