title: xcodebuild fails on the 'write auxiliary files' step
body: <p>I am doing a clean then archive:</p>
  
  <pre><code>xcodebuild -workspace MyApp.xcworkspace \
             -scheme MyScheme \
             -archivePath /Library/......./outputfolder/MyApp.xcarchive \
             clean archive
  </code></pre>
  
  <p>I get this error about 50% of the time.  </p>
  
  <pre><code>The following build commands failed:
      Write auxiliary files
  </code></pre>
  
  <p>Its reported twice in the apple developer forums (but not yet on StackOverflow as far as I am aware).</p>
  
  <ul>
  <li><a href="https://devforums.apple.com/message/938564#938564">https://devforums.apple.com/message/938564#938564</a></li>
  <li><a href="https://devforums.apple.com/message/953949#953949">https://devforums.apple.com/message/953949#953949</a></li>
  </ul>
  
  <p>Has anyone found the cause or a workaround?</p>