You would have to add "apt-setup/proposed=true" (without the quotes) somewhere on the append line. Another option is to put the line in your preseed/kickstart file, I'm not sure about the syntax then.
You would have to add "apt-setup/ proposed= true" (without the quotes) somewhere on the append line. Another option is to put the line in your preseed/kickstart file, I'm not sure about the syntax then.