message: Allow overriding libtpu loading via environment variable.
diff: @@ -21,6 +21,7 @@ limitations under the License.
  #include <unistd.h>
  #endif // LIBTPU_ON_GCE
  +#include "absl/strings/str_cat.h"
  #include "absl/strings/str_split.h"
  #include "absl/synchronization/mutex.h"
  #include "tensorflow/core/platform/logging.h"
  @@ -37,6 +38,14 @@ bool TryAcquireTpuLock() {
  static bool should_load_library = false;
  if (!attempted_file_open) {
  + std::string load_library_override =
  + absl::StringCat(getenv("TPU_LOAD_LIBRARY"));
  +
  + if (load_library_override == "true") {
  + return true;
  + } else if (load_library_override == "false") {
  + return false;
  + }
  should_load_library = true;
  // if the TPU_HOST_BOUNDS env var is set, that means we are loading each
  