title: Git submodule inside of a submodule (nested submodules)
body: <p>Is it possible for a git submodule to be made of several other git submodules, and the super git repo to fetch the contents for each submodule?</p>
  
  <p>I have tried to do this using the obvious/naive approach of creating a git repo holding several submodules.</p>
  
  <p>Then adding this git repo to another git repo as a submodule.</p>
  
  <p>Then attempting to pull from the root directory of the super git repo by <code>git submodule init</code> and then <code>git submodule update</code>.  But this fails to fetch the sub-submodules.</p>