Fix bug where we weren't properly caching enum values and we were always looking up the media type when constructing manifests

endpoints/api/tag.py

@@ -37,6 +37,7 @@ def _tag_dict(tag):
   # TODO(jschorr): Remove this check once fully on OCI data model.
   if tag.manifest_digest:
     tag_info['manifest_digest'] = tag.manifest_digest
+
     if tag.manifest:
       try:
         tag_info['manifest'] = json.loads(tag.manifest.internal_manifest_bytes.as_unicode())