https://apis-explorer.appspot.com/apis-explorer/?base=https://luci-config.appspot.com/_ah/api#p/config/v1/config.get_config_sets?config_set=projects%252Ffuchsia-maxwell&include_files=true&include_last_import_attempt=true&_h=3&

returns HTTP 500 for me

Log:

Encountered unexpected error from ProtoRPC method implementation: ValueError (ancestor cannot be an incomplete key) (/base/data/home/runtimes/python27/python27_lib/versions/third_party/protorpc-1.0/protorpc/wsgi/service.py:191)
Traceback (most recent call last):
  File "third_party/protorpc-1.0/protorpc/wsgi/service.py", line 181, in protorpc_service_app
    response = method(instance, request)
  File "components/auth/endpoints_support.py", line 218, in wrapper
    return method(service, *args, **kwargs)
  File "third_party/endpoints-1.0/endpoints/api_config.py", line 1331, in invoke_remote
    return remote_method(service_instance, request)
  File "third_party/protorpc-1.0/protorpc/remote.py", line 414, in invoke_remote_method
    response = method(service_instance, request)
  File "components/auth/endpoints_support.py", line 173, in wrapper
    return func(service, *args, **kwargs)
  File "api.py", line 174, in get_config_sets
    request.config_set, latest_revisions[request.config_set])
  File "storage.py", line 112, in get_file_keys
    ancestor=ndb.Key(ConfigSet, config_set, Revision, revision)).fetch()
  File "appengine/ext/ndb/model.py", line 3435, in _query
    qry = Query(kind=cls._get_kind(), **kwds)
  File "appengine/ext/ndb/utils.py", line 160, in positional_wrapper
    return wrapped(*args, **kwds)
  File "appengine/ext/ndb/query.py", line 827, in __init__
    raise ValueError('ancestor cannot be an incomplete key')
ValueError: ancestor cannot be an incomplete key