Fix workers without metadata stream

This is a temporary hack until the different stream naming schemes
become obsolete due to further improvements like acknowledgements.

src/AsapoWorker/streamer.py

@@ -50,6 +50,7 @@ def get_new_stream(stream, receiver_stream_list, metadata_stream_list,
 
     receiver_stream_list = sorted(receiver_stream_list, key=lambda x: x['timestampCreated'])
     receiver_stream_list = [x['name'] for x in receiver_stream_list]
+    if not isinstance(metadata_stream_list, ContainsAll):
         metadata_stream_list = [x['name'] for x in metadata_stream_list]
     if 'basename' in naming_scheme:
         if sender_stream_list is None: