message: Add offset == 0
diff: @@ -98,7 +98,8 @@ static void SyncImpl(const std::string& bucket, const std::string& object,
  int64_t* offset, TempFile* outfile,
  gcs::Client* gcs_client, TF_Status* status) {
  outfile->operator<<(std::flush);
  - if (*offset == -1) {
  + // `*offset == 0` means this file does not exist on the server.
  + if (*offset == -1 || *offset == 0) {
  // UploadFile will automatically switch to resumable upload based on Client
  // configuration.
  auto metadata = gcs_client->UploadFile(outfile->getName(), bucket, object);
  