message: horovod_test: Allow running mpirun as root
  Summary:
  The buildbot runs the tests as root.
  Ref T21761.
  Test Plan: Test now passes in local Ubuntu buildbot.
  Reviewers: #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, georgep
  Maniphest Tasks: T21761
diff: @@ -226,7 +226,10 @@ if __name__ == "__main__":
  # Already in MPI context, run the tests.
  test.main()
  else:
  - # Run this file in MPI context.
  - mpirun = ["mpirun", "--tag-output", "-np", str(NUM_WORKERS)]
  + # Run this file in MPI context (buildbot runs as root).
  + mpirun = [
  + "mpirun", "--allow-run-as-root", "--tag-output", "-np",
  + str(NUM_WORKERS)
  + ]
  cmd = ["python", __file__]
  subprocess.check_output(mpirun + cmd)
  