Merge remote-tracking branch 'origin/master' into nomenclature

Conflicts:
	test/data/test.db
	workers/dockerfilebuild.py

workers/dockerfilebuild.py

@@ -223,7 +223,6 @@ class DockerfileBuildContext(object):
         raise RuntimeError(message)
 
   def pull(self):
-    # Pull the image, in case it was updated since the last build
     image_and_tag_tuple = self._parsed_dockerfile.get_image_and_tag()
     if image_and_tag_tuple is None or image_and_tag_tuple[0] is None:
       self._build_logger('Missing FROM command in Dockerfile', build_logs.ERROR)