new_contents: # Hack: There is no official EncodeVarint function provided by protobuf. The
  # one we use here is technically private. If it is removed or becomes
  # troublesome to update -- we'll have to do it ourselves.
  #
  # See http://code.google.com/p/protobuf/issues/detail?id=226
  import google.protobuf.internal.encoder as enc
  from google.protobuf.internal.encoder import _EncodeVarint
  
  # encode encodes the unsigned varint i, and returns the encoded data as
  # a str.
  def encode(i):
      buf = []
  	# Note: The signed variant is named "_EncodeSignedVarint".
      _EncodeVarint(buf.append, i)
      return "".join(buf)
  
  
subject: add a workaround for lack of official varint support.