Code review fixes

workers/manifestbackfillworker.py

@@ -75,6 +75,13 @@ class BrokenManifest(ManifestInterface):
   def generate_legacy_layers(self, images_map, lookup_config_fn):
     return None
 
+  def get_v1_compatible_manifest(self, namespace_name, repo_name, tag_name, lookup_fn):
+    return self
+    
+  @property
+  def schema_version():
+    return 1
+
 
 class ManifestBackfillWorker(Worker):
   def __init__(self):