function decodeChangeMeta(buffer, computeHash) {
  if (buffer[8] === CHUNK_TYPE_DEFLATE) buffer = inflateChange(buffer)
  const header = decodeContainerHeader(new Decoder(buffer), computeHash)
  if (header.chunkType !== CHUNK_TYPE_CHANGE) {
    throw new RangeError("Buffer chunk type is not a change")
  }
  const meta = decodeChangeHeader(new Decoder(header.chunkData))
  meta.change = buffer
  if (computeHash) meta.hash = header.hash
  return meta
}
Decodes the header fields of a change in binary format, but does not decode
the operations. Saves work when we only need to inspect the headers. Only
computes the hash of the change if `computeHash` is true.