title: How do I disable git subtree pull if nothing is new
body: <p>I have a git repository <strong>subtools</strong> that I handle through <a href="/questions/tagged/git-subtree" class="post-tag" title="show questions tagged &#39;git-subtree&#39;" rel="tag">git-subtree</a> inside my main project <strong>sf-parent</strong>.</p>
  
  <p>I have a problem with the following command</p>
  
  <pre><code>git subtree pull -P subtree/subtools subtools v3.0.3 --squash
  </code></pre>
  
  <p><code>v3.0.3</code> is a git tag.</p>
  
  <p>The problem is that the command never tells me that nothing's new to pull, however is pulls anyway and thus adds new commits to my <strong>sf-parent</strong> project.</p>
  
  <p>This is very weird because it hasn't happen before.</p>
  
  <p>How do I tell <a href="/questions/tagged/git-subtree" class="post-tag" title="show questions tagged &#39;git-subtree&#39;" rel="tag">git-subtree</a> to pull only if something's changed?</p>
  
  <p><strong>UPDATE</strong></p>
  
  <p>Maybe should I leave <code>git subtree</code> and use <code>git read-tree</code> instead?</p>