title: Find merge commit which include a specific commit
body: <p>Imagine the following history:</p>
  
  <pre><code>       c---e---g--- feature
        /         \
  -a---b---d---f---h--- master
  </code></pre>
  
  <p>How can I find when commit "c" has been merged into master (ie, find merge commit "h") ?</p>