readline error when saving interactive command history when history file path is a symlink to a relative path

Bug report

Bug description:

To reproduce the issue

1. Set up home directory like following:

$HOME/
  .python_history --> foo/history_file
  foo/
    history_file

2. Launch a Python interactive session with CWD different from $HOME
3. Execute the following

import readline
import os
history_path=os.path.expanduser("~/.python_history")
assert os.path.exists(history_path)
readline.write_history_file(history_path)

4. Observe the following error

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
FileNotFoundError: [Errno 2] No such file or directory

Possible cause

This is likely due to how GNU readline commits history information to file. As of GNU readline v8.2 (used in Python 3.10 and 3.12 among others), it creates a temporary file in the parent directory of the history file, write to that temporary file, and then rename the temporary file to the history file. See history_tempfile in histfile.c of GNU readline.

GNU readline determines the parent directory from the readlink output of the user-supplied history file path. In this case, since the history file is a symlink with a relative path, the parent directory is resolved to the relative path foo/. If foo/ doesn't exist in the CWD, history saving fails.

CPython versions tested on:

3.10, 3.12

Operating systems tested on:

Linux

從使用相對目標的符號連結，並將工作目錄設為不同於 $HOME 的目錄開始重現。閱讀 histfile.c 中 GNU readline 的 history_tempfile 邏輯，並追蹤 CPython's readline.write_history_file 如何到達該邏輯。完成標準是在經過測試的 Linux 設定上，針對所述符號連結配置儲存歷史記錄能夠成功，並為該情況提供回歸涵蓋。