Test that has child process logging to stdout not consistent when run with python -m unittest vs nose2

I have a command line command that I'm trying to write an end-to-end test for to make sure everything is working well. I wanted to invoke the CLI via a multiprocessing.Process, because when the CLI starts running it configures the root logger, and I want to test that, along with everything else, without creating inconsistencies in my test suite. Below is a simple of the type of test I'm interested in doing. You can see that I have child, which is the entrypoint of my CLI, you can see that it configures logging, and also that it makes a couple of print statements. The test itself verifies both the print statement and the log message show up in stdout, which is redirected to a file in a child process.

When I run this test with unittests, everything passes. When I run with nose2, I get a failure. See below for details.

tests/test_example.py

import logging
import sys
import tempfile
import unittest

from pathlib import Path
from multiprocessing import Process


def child():
    logging.basicConfig(
        handlers=[logging.StreamHandler(sys.stdout)],
        level=logging.INFO,
        format="%(message)s",
        datefmt="%Y-%m-%dT%H:%M:%S%z",
    )

    print("MY PRINT STATEMENT")
    logging.info("MY LOG MESSAGE")


def child_wrapper(target, stdout_file, stderr_file):
    sys.stdout = stdout_file.open("w")
    sys.stderr = stderr_file.open("w")

    try:
        target()
    finally:
        sys.stdout.flush()
        sys.stderr.flush()


class TestLoggingInChildProc(unittest.TestCase):
    def test_logging_in_child_proc(self):
        with tempfile.TemporaryDirectory() as d:
            stdout_file = Path(f"{d}/stdout.txt")
            stderr_file = Path(f"{d}/stderr.txt")

            p = Process(
                target=child_wrapper,
                args=[child, stdout_file, stderr_file],
            )
            p.start()
            p.join()
            p.close()

            self.assertEqual(
                "MY PRINT STATEMENT\nMY LOG MESSAGE",
                stdout_file.read_text().strip()
            )

            self.assertEqual("", stderr_file.read_text().strip())

When I run tree ., I see:

.
└── tests
    ├── __init__.py
    └── test_example.py

1 directory, 2 files

When I run python -m unittest tests.test_example the test passes, but when I run nose2 test_example the test fails. Here is the failure text:

F
======================================================================
FAIL: test_logging_in_child_proc (tests.test_example.TestLoggingInChildProc)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/tmp/tests/test_example.py", line 47, in test_logging_in_child_proc
    self.assertEqual(
AssertionError: 'MY PRINT STATEMENT\nMY LOG MESSAGE' != 'MY PRINT STATEMENT'
- MY PRINT STATEMENT
?                   -
+ MY PRINT STATEMENT- MY LOG MESSAGE

----------------------------------------------------------------------
Ran 1 test in 0.004s

FAILED (failures=1)

When I invoke this test using python -m unittest test_example.py the test passes. However, when I invoke this script using nose2