InterpreterPoolExecutor workers do not inherit modifications made to sys.path before starting.

Bug report

Bug description:

All existing executors will reflect modifications to sys.path in the child thread/process/whatever that gets started. However the new InterpreterPoolExecutor is not copying this behavior, leading to unexpected import errors when for example running sub-intepreters inside of pytest, as the test directory is added to the sys.path in the parent interpreter but will be lost in the sub-interpreter.

This is easily worked around by using an initializer:

pool = InterpreterPoolExecutor(
        max_workers=queue.concurrency,
        initializer=on_initialize_worker,
        initargs=(sys.path,),
 )
 
 def on_initialize_worker(parent_sys_path: list[str]):
        """
        This method is called in each worker before it begins running jobs.
        It can be used to perform any necessary setup, such as loading NLTK
        datasets or calling ``django.setup()``.

        By default, it replaces the running job's ``sys.path`` with the workers.
        """
        # Unlike all other executors, the InterpreterPoolExecutor does not
        # automatically inherit the parent process's sys.path. This is a
        # workaround to ensure that the worker has the same sys.path as the
        # parent process or tests will fail.
        sys.path = parent_sys_path

This behavior makes sense for sub-interpreters themselves, but probably not for the InterpreterPoolExecutor.

cc. @ericsnowcurrently

CPython versions tested on:

3.13, 3.14

Operating systems tested on:

Linux

Empieza localizando la implementación de CPython y las pruebas de InterpreterPoolExecutor, y después compara cómo los ejecutores existentes gestionan los cambios en sys.path del proceso padre antes de que se inicien los workers. Reproduce el fallo de importación informado añadiendo una ruta antes de crear el ejecutor. Se considera terminado cuando los workers hereden esa ruta modificada sin requerir un initializer, con cobertura de regresión para el comportamiento de Python 3.13 y posteriores.