Make sure images in the process of being uploaded are not scanned by Clair

data/registry_model/manifestbuilder.py

@@ -145,6 +145,7 @@ class _ManifestBuilder(object):
   def assign_layer_blob(self, layer, blob, computed_checksums):
     """ Assigns a blob to a layer. """
     assert blob
+    assert not blob.uploading
 
     repo_image = model.image.get_image_by_db_id(layer.db_id)
     if repo_image is None: