All submodules have hydrogen branch now. And we added a new script to the tools/ dir: “clone-full”.
That script clones all submodules automatically and switches branch to the current branch of build-iso, so use like this (if you want all submodules):
git clone https://github.com/vyos/build-iso.git
cd build-iso
git branch hydrogen --track origin/hydrogen
git checkout hydrogen./tools/clone-full