After the initial install of VyOS 1.2 (Build: 999.2016123)
When running install image with either the path to an ISO or a URL you get:
vyos@vyos-1-2-primary:~$ install image /config/vyos-1.1.7-amd64.iso
Invalid command: install image [/config/vyos-1.1.7-amd64.iso]
vyos@vyos-1-2-primary:~$ install image http://packages.vyos.net/iso/release/1.1.7/vyos-1.1.7-amd64.iso
Invalid command: install image [http://packages.vyos.net/iso/release/1.1.7/vyos-1.1.7-amd64.iso]