Skip queuing build tasks for UNMATCHED images

Closes-Bug: #1639989

Change-Id: I7bad2b784d2ac02a5af0d790ea32d35f90a681ec

kolla/image/build.py

@@ -927,6 +927,11 @@ class KollaWorker(object):
         queue = six.moves.queue.Queue()
 
         for image in self.images:
+            if image.status == STATUS_UNMATCHED:
+                # Don't bother queuing up build tasks for things that
+                # were not matched in the first place... (not worth the
+                # effort to run them, if they won't be used anyway).
+                continue
             if image.parent is None:
                 queue.put(BuildTask(self.conf, image, push_queue))
                 LOG.info('Added image %s to queue', image.name)