unknown error with scheduler=shell

[Thomas-Bontemps]

I use the option --scheduler=shell to run the tests defined in the following test file named test.py :

import time
import pytest_parallel

@pytest_parallel.mark.parallel(1)
def test_1(comm):
    time.sleep(3)

@pytest_parallel.mark.parallel(1)
def test_2(comm):
    time.sleep(3)

@pytest_parallel.mark.parallel(1)
def test_3(comm):
    time.sleep(3)

Then I run the following command in the terminal :
pytest --n-workers=3 --scheduler=shell test.py

I tried to do it on two linux machines. It works well on the first one but returns the following error on the other one (my onera local machine):

I checked the log files like .pytest_parallel/tmpmt02m8c4/test.py__test_1 but they are all empty.

[BerengerBerthoul]

It seems to come from OpenMPI 4.0.5

Reproducer :

from mpi4py import MPI
import subprocess
p = subprocess.run('mpirun -np 1 echo hello', shell=True)
print('p.returncode = ',p.returncode)

Prints hello and returns 0 with OpenMPI 5.0.2, but prints nothing and returns 1 with OpenMPI 4.0.5

[BerengerBerthoul]

Not a complete fix, but #18 allows for a better reporting of the error.