title: Changed found in source tree from non-changed storyboard/xib
body: <p>I am using source tree to manage the version control, a strange thing happened on storyboard/xib. </p>
  
  <p>Source tree detected changes in storyboard/xib files even if I only click the storyboard/xib, not even moving anything in it.</p>
  
  <p>I discard the changes every time if I am not adding or moving stuff in it. But I wonder if I take the changes in the storyboard, is it OK or not? Or there is no difference?</p>
  
  <p>I also wonder what is the reason this happens.</p>
  
  <p>Thanks for any reply.</p>
  
  <p>Edit: the changes are on the <code>toolsVersion = "..."</code> as well as the <code>dependency version</code></p>