Bug report

Bug description:

The current completion logic in Lib/_pyrepl/completing_reader.py uses a suffix-insertion strategy (source code):

In the contrast, Readline completely replaces user input with the candidate (source code).

This will lead to unwanted behavior in case-insensitive completion scenario. If user input 'xy', they might get 'xyZZY' instead of the expected 'XYZZY'.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-145392: Fix _pyrepl completion to replace input stem instead of appending #145393