I don't think there are submodules in ABC's repo. At least there are none in Core, so ABC would have had to had to add submodules recently. It won't do anything to initialized submodules on a repo that has none, but I'd rather people know that this step has no effect. That aside, this is a acceptable procedure. Note that you can verify a tag without checking it out. It's actually preferable to first verify the signature on the tag then to check it out than otherwise.