message: [TF] TFRecordWriter.flush() now flushes the file (not just the zlib buffer).
  Previously
diff: @@ -68,6 +68,11 @@ void PyRecordWriter::Flush(TF_Status* out_status) {
  return;
  }
  Status s = writer_->Flush();
  + if (s.ok()) {
  + // Per the RecordWriter contract, flushing the RecordWriter does not
  + // flush the underlying file. Here we need to do both.
  + s = file_->Flush();
  + }
  if (!s.ok()) {
  Set_TF_Status_from_Status(out_status, s);
  return;
  