title: XCode 7.2.1 - cdtool cannot compile occurs irregularly
body: <p>The app I am developing has a weird issue since a few months. Sometimes during building an archive the error <code>cdtool cannot compile</code> occurs. But only sometimes.
  When I wipe the derived-data and do a clean-archive it works again.</p>
  
  <p>I found a variety of people asking similar questions, but they all had this error occur nonstop. </p>
  
  <p>To be precise: The error occurs always during archiving and always on the same file which is <strong>Config.xcdatamodel</strong>. This CoreData model only has one version so version-conflicts aren't a problem (also verified on the file-system).</p>
  
  <p>Unfortunately it is nearly not reproducable at all, it seems to occur 100% randomly. It also doesn't provide an closer information about what exactly it is, that fails.</p>
  
  <p><a href="https://i.stack.imgur.com/rmSIG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rmSIG.png" alt="enter image description here"></a></p>
  
  <p>In the image there are two compile-errors. Thats because the <strong>Config.xcdatamodel</strong> that fails, is in both targets. They won't be used at the same time, so it should be fine. I also suspect that the second error-message is based on the first (upper) one.</p>
  
  <p>Did anyone ever observe such a behaviour? I'm currently using XCode 7.2.1</p>