Related to https://github.com/apache/airflow/issues/9655

It would be nice to add a message when you get this error with some info, like 'This probably is because a lack of RAM' or something like that. 

I have found the code where the -9 is assigned but have no idea how to add a logging message. 

        self.process = None

        if self._rc is None:
            # Something else reaped it before we had a chance, so let's just "guess" at an error code.
            self._rc = -9
tests/task/task_runner/test_standard_task_runner.py
#
#
#
import getpass
import logging
import os
import time
import unittest
from logging.config import dictConfig
from unittest import mock
import psutil
from airflow import models, settings
from airflow.jobs.local_task_job import LocalTaskJob
from airflow.models import TaskInstance as TI
from airflow.task.task_runner.standard_task_runner import StandardTaskRunner
from airflow.utils import timezone
from airflow.utils.state import State
from tests.test_utils.db import clear_db_runs
TEST_DAG_FOLDER = os.environ['AIRFLOW__CORE__DAGS_FOLDER']
DEFAULT_DATE = timezone.datetime(2016, 1, 1)