title: How to write git commit messages for submodule updates?
body: <p>I always struggle to write good git commit messages for commits which did nothing except update which commit a submodule is on. What I really want to write is "just read the freaking submodule commit messages!" </p>
  
  <p>Perhaps a slightly nicer solution is, does there exist something which goes to the submodule and concatenates all of the messages since the previous commit it was on in some nice fashion and automatically makes <em>that</em> the message?</p>