docstr: Tests that impersonation using a unix user works with custom packages in PYTHONPATH.
docstr_tok: ["Tests","that","impersonation","using","a","unix","user","works","with","custom","packages","in","PYTHONPATH","."]
code: def test_impersonation_custom(self, monkeypatch):
      """
      Tests that impersonation using a unix user works with custom packages in PYTHONPATH.
      """
      monkeypatch.setenv("PYTHONPATH", TEST_UTILS_FOLDER)
      assert TEST_UTILS_FOLDER not in sys.path
      self.run_backfill(
          "impersonation_with_custom_pkg", "exec_python_fn"
      )
  
imports: from __future__ import annotations
  import contextlib
  import logging
  import os
  import subprocess
  import sys
  import tempfile
  from pathlib import Path
  import pytest
  from airflow.configuration import conf
  from airflow.jobs.backfill_job_runner import BackfillJobRunner
  from airflow.jobs.job import Job, run_job
  from airflow.models import DagBag, DagRun, TaskInstance
  from airflow.utils.db import add_default_pool_if_not_exists
  from airflow.utils.state import State
  from airflow.utils.timezone import datetime
  from airflow.utils.types import DagRunType
  from tests.test_utils import db
label_desc: Use image node_id 2 for calling the TestImpersonationWithCustomPythonPath obj's underlying member method code with example usage: obj.test_impersonation_custom(monkeypatch) without return types