Subject: 30.1; python-inferior-mode: completion regression

From: Christian Sattler <[email-masked]>
Date: Wed, 16 Apr 2025 21:59:01 +0200

Completing a non-existing prefix attempts to complete it as a filename.

Steps to reproduce:

1. touch test.file
2. emacs -Q
3. M-x run-python
4. test
5. M-x python-shell-completion-complete-or-indent

Outcome: incorrectly completes to test.file.

This regression was introduced in commit 0b9c714. The function
python-shell-completion-at-point now returns nil instead of an empty
list of candidates. This causes the next element of
completion-at-point-functions list to be tried. This is
comint-completion-at-point and completes filenames, which does not
make sense in this context.