title: xcode: resolve merge conflicts failed
body: <p>I try to merge two branches with Xcode. I get conflict, and I use "let then right" button to reconcile conflict. But when I click "merge", Xcode shows the error </p>
  
  <pre><code>fatal: You have not concluded your merge (MERGE_HEAD exists).
  Please, commit your changes before you merge.
  </code></pre>
  
  <p>Here is the screenshot
  <a href="https://i.stack.imgur.com/mTitP.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mTitP.jpg" alt="enter image description here"></a></p>