The way I read it, it seems to claim that github will just "insert" a known object with that hash into the new repository when it's pushed, though I'm somewhat

The way I read it, it seems to claim that github will just "insert" a known object with that hash into the new repository when it's pushed, though I'm somewhat confused as to how this would work, or how the submodule trick even adds the hash to the commit log in the first place. EDIT: I read the article again and couldn't find any of that, so I must have read that in a comment here on HN instead.