old_contents: import update_object_pb2
  
  class UpdateObject(object):
      data_members = [parents, data]
      def __init__(self, parents, data):
          self.parents = parents
          self.data = data
          self._sha1 = None
  
      @property
      def sha1(self):
          if self._sha1:
              return self._sha1
          # XXX Calculate sha1 of this object
  
      @staticmethod
      def from_object(obj):
          """Convert an object straight from Git into a RootObject"""
          protobuf = update_object_pb2.UpdateObject()
          protobuf.ParseFromString(obj)
          return UpdateObject(protobuf.parents, protobuf.data)
  
      def as_object(self):
          """Convert a RootObject into data suitable to write into the database
          as a Git object"""
          protobuf = update_object_pb2.UpdateObject()
          for member in self.data_members:
              setattr(protobuf, member, getattr(self, member))
          return protobuf.SerializeToString()
  
new_contents: import update_object_pb2
  
  class UpdateObject(object):
      data_members = ["parents", "data"]
      def __init__(self, parents, data):
          self.parents = parents
          self.data = data
          self._sha1 = None
  
      @property
      def sha1(self):
          if self._sha1:
              return self._sha1
          # XXX Calculate sha1 of this object
  
      @staticmethod
      def from_object(obj):
          """Convert an object straight from Git into a RootObject"""
          protobuf = update_object_pb2.UpdateObject()
          protobuf.ParseFromString(obj)
          return UpdateObject(protobuf.parents, protobuf.data)
  
      def as_object(self):
          """Convert a RootObject into data suitable to write into the database
          as a Git object"""
          protobuf = update_object_pb2.UpdateObject()
          for member in self.data_members:
              setattr(protobuf, member, getattr(self, member))
          return protobuf.SerializeToString()
  
subject: fix typos in data members