title: iOS CI fails with "CoreUI: CUICatalog: couldn't get 'kMGArtworkGraphicsFeatureSetFallbacks' from MGCopyAnswer got"
body: <p>Keep getting thousands of these logs in our CI system since upgrading to Xcode 7. Don't have the slightest clue what they could mean.</p>
  
  <pre><code>2015-09-16 13:44:36.286 Interface Builder Cocoa Touch Tool[5197:11683] CoreUI: CUICatalog: couldn't get 'kMGArtworkGraphicsFeatureSetClass' from MGCopyAnswer got '{
      ArtworkDeviceIdiom = pad;
      ArtworkDeviceScaleFactor = "-1";
      DevicePerformanceMemoryClass = 1;
  }'
  2015-09-16 13:44:36.287 Interface Builder Cocoa Touch Tool[5197:11683] CoreUI: CUICatalog: couldn't get 'kMGArtworkGraphicsFeatureSetFallbacks' from MGCopyAnswer got '{
      ArtworkDeviceIdiom = pad;
      ArtworkDeviceScaleFactor = "-1";
      DevicePerformanceMemoryClass = 1;
  }'
  2015-09-16 13:44:36.288 Interface Builder Cocoa Touch Tool[5197:11683] CoreUI: CUICatalog: couldn't get 'kMGArtworkGraphicsFeatureSetClass' from MGCopyAnswer got '{
      ArtworkDeviceIdiom = pad;
      ArtworkDeviceScaleFactor = "-1";
      DevicePerformanceMemoryClass = 1;
  }'
  </code></pre>
  
  <p>x 1000</p>