title: Show non-merge differences for two commits in git
body: <p>I have two commits, once of which is the ancestor of another. (They happen to be the start and end points of a branch. I don't think that matters, but I'll include it if it does).</p>
  
  <p>I want to see the diff between the two commits, but <em>excluding</em> changes made during merge commits (that is, all commits with more than one parent) that were made between the two commits. (Basically, I want any "real" commit that was made to the branch, excluding the merges.)</p>
  
  <p>Is this possible? If so, how do you accomplish this?</p>
  
  <p>If necessary, assume that there are no conflicts resolved during the merge commits... but bonus points for a solution that can handle them elegantly.</p>