title: Undo git Auto-merge
body: <p>After I switched branches, I applied stash (as below), which resulted in an auto-merge. </p>
  
  <pre><code>  git stash apply
  
  Auto-merging src/clojure/project_src.clj
  On branch upgrade_project
  Changes not staged for commit:
    (use "git add &lt;file&gt;..." to update what will be committed)
    (use "git checkout -- &lt;file&gt;..." to discard changes in working directory)
  
  modified:   src/clojure/project_src.clj
  
  no changes added to commit (use "git add" and/or "git commit -a")
  </code></pre>
  
  <p>I tried <code>git revert HEAD</code> which reverted a commit (not the auto-merge). How can I revert the auto-merge? </p>