Readline: importting `pathlib` breaks libedit `readline.read_init_file` when `.editrc`'s comments are longer than 20 characters

Bug report

Bug description:

Environment

macOS Sonoma 14.3.1
Python 3.12.2
Libedit readline (I tested with my Linux VM and seems that the same bug doesn't appear for libreadline)

Bug Description

When reading .editrc for libedit readline with readline.read_init_file in python startup script, if both these two conditions are true:

1. Python startup script imports pathlib
2. .editrc contains comments with more than 21 characters

.editrc will not be applied to Python REPL. Manually typing readline.read_init_file again in REPL works though.

How to Reproduce the Bug

1. Create a minimal python startup script with these lines:

import pathlib
import readline

readline.read_init_file('/path/to/your/editrc')

4. Create a minimal .editrc to test if it is applied (I'm using 1's and bind -v here but you can change them to whatever you want, as long as the comment exceeds 20 characters):

#11111111111111111111

bind -v

5. Open your terminal and test whether Vi mode is applied.
6. (extra) If you break the comment in .editrc into multiple lines, but not adding any 1, it still breaks:

#11111111
#111111111111

bind -v

or

#1111
#1111

bind -v

#1111111
#11111

CPython versions tested on:

3.12

Operating systems tested on:

Linux, macOS

まず、Pythonの起動スクリプト、pathlib、readline.read_init_file、およびlibedit上で20文字を超えるコメントを含む.editrcを使って問題を再現します。readline.read_init_fileの経路を追跡し、pathlibのインポート時に.editrcの設定が適用されることを確認します。再現が失敗しなくなり、既存の動作が維持されれば完了です。