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

まず CPython の InterpreterPoolExecutor の実装とテストを見つけ、既存の executor が worker の起動前に親プロセスの sys.path の変更をどのように扱っているかを比較します。executor を作成する前にパスを追加して、報告されたインポート失敗を再現します。initializer を必要とせずに worker が変更後のパスを継承し、Python 3.13 以降の動作に対するリグレッションカバレッジがあることを完了条件とします。