message: Update bigtable_lib.cc
  grpc_code was assigned and not used, probably a small bug.
diff: @@ -27,7 +27,7 @@ Status GrpcStatusToTfStatus(const ::grpc::Status& status) {
  status.error_code() == ::grpc::StatusCode::OUT_OF_RANGE) {
  grpc_code = ::grpc::StatusCode::INTERNAL;
  }
  - return Status(static_cast<::tensorflow::error::Code>(status.error_code()),
  + return Status(static_cast<::tensorflow::error::Code>(grpc_code),
  strings::StrCat("Error reading from Cloud Bigtable: ",
  status.error_message()));
  }
  