old_contents: from numba.np.ufunc.parallel import get_thread_count
  from os import environ as env
  from numba.core import config
  import unittest
  
  
  class TestParallelEnvVariable(unittest.TestCase):
      """
      Tests environment variables related to the underlying "parallel"
      functions for npyufuncs.
      """
  
      _numba_parallel_test_ = False
  
      def test_num_threads_variable(self):
          """
          Tests the NUMBA_NUM_THREADS env variable behaves as expected.
          """
          key = 'NUMBA_NUM_THREADS'
          current = str(getattr(env, key, config.NUMBA_DEFAULT_NUM_THREADS))
          threads = "3154"
          env[key] = threads
          try:
              config.reload_config()
          except RuntimeError as e:
              # This test should fail if threads have already been launched
              self.assertIn("Cannot set NUMBA_NUM_THREADS", e.args[0])
          else:
              try:
                  self.assertEqual(threads, str(get_thread_count()))
                  self.assertEqual(threads, str(config.NUMBA_NUM_THREADS))
              finally:
                  # reset the env variable/set to default
                  env[key] = current
                  config.reload_config()
  
  if __name__ == '__main__':
      unittest.main()
  
new_contents: from numba.np.ufunc.parallel import get_thread_count
  from os import environ as env
  from numba.core import config
  import unittest
  
  
  class TestParallelEnvVariable(unittest.TestCase):
      """
      Tests environment variables related to the underlying "parallel"
      functions for npyufuncs.
      """
  
      _numba_parallel_test_ = False
  
      def test_num_threads_variable(self):
          """
          Tests the NUMBA_NUM_THREADS env variable behaves as expected.
          """
          key = 'NUMBA_NUM_THREADS'
          current = str(getattr(env, key, config.NUMBA_DEFAULT_NUM_THREADS))
          threads = "3154"
          env[key] = threads
          try:
              config.reload_config()
          except RuntimeError as e:
              # This test should fail if threads have already been launched
              self.assertIn("Cannot set NUMBA_NUM_THREADS", e.args[0])
          else:
              self.assertEqual(threads, str(get_thread_count()))
              self.assertEqual(threads, str(config.NUMBA_NUM_THREADS))
          finally:
              # reset the env variable/set to default. Should not fail even if
              # threads are launched because the value is the same.
              env[key] = current
              config.reload_config()
  
  if __name__ == '__main__':
      unittest.main()
  
subject: Fix the parallel env variable test to reset the env correctly