[issue41814] Mismatch between the manipulation of `sys.path` by `runpy` and by the Python command-line interface

[Géry]

New submission from Géry <gery.ogam at gmail.com>:

Nicholas, I have noticed that `runpy.run_path` alters `sys.path` as expected for a file_path argument which is a valid `sys.path` entry (typically a directory or zip file). That is to say it adds the file_path argument to the beginning of `sys.path`, like `python <valid sys.path entry>`.

However, I have also noticed that `runpy.run_path` does not alter `sys.path` as expected for a file_path argument which is a Python source or bytecode file path. That is to say it does not add the *parent path* of the file_path argument to the beginning of `sys.path`, contrary to `python <source or bytecode file path>`.

Likewise, I have also noticed that `runpy.run_module` (with the alter_sys argument set to `True` of course) does not alter `sys.path` as expected. That is to say it does not add the path of the *current directory* to the beginning of `sys.path`, contrary to `python -m <module>`.

Only the first of the three previous `sys.path` manipulations is documented in https://docs.python.org/3/library/runpy.html though, so the `runpy` implementation is at least compliant with its specification. So is the mismatch between the manipulation of `sys.path` by `runpy` and by the Python command-line interface a specification bug or is it the intended behaviour?

----------
components: Library (Lib)
messages: 377171
nosy: maggyero, ncoghlan
priority: normal
severity: normal
status: open
title: Mismatch between the manipulation of `sys.path` by `runpy` and by the Python command-line interface
type: behavior
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue41814>
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