title: git submodule merge conflict: how to visualize?
body: <p>I was pretty happy when I found out lately about</p>
  
  <pre><code>git submodule summary
  </code></pre>
  
  <p>which shows me nicely by which commits the checked out commit of a submodule is ahead or behind the reference in the repository.</p>
  
  <p>Now when I am in the middle of a merge with submodule conflicts, the same command does not produce useful output. I need a painful sequence of gitk in my main tree examining the branches, along with cd'ing into the submodules, fetching and  gitk in there, comparing sha1 values...</p>
  
  <p>What would be a more convenient way to get the picture of the conflict?</p>