Python 3.13+ REPL inserts ~ on [Del] [PgUp] [PgDn] with TERM=vt100

[hroncok]

Bug report

Bug description:

I've noticed that the Python 3.13+ REPL misbehaves in a mock shell environment. Whenever I press Del, PgUp, or PgDn, a literal ~ character is inserted.

tl;dr this happens when you run TERM=vt100 python3.13.

Details:

I did not know what was special about the mock shell, but this did not happen with the old readline-based REPL.

When trying to figure out what's different in the mock shell I looked at env and it was:

SHELL=/bin/bash
HISTCONTROL=ignoredups
HISTSIZE=1000
HOSTNAME=2f26bd11c076
PWD=/builddir
LOGNAME=root
HOME=/builddir
LANG=C.UTF-8
LS_COLORS=...snip...
PROMPT_COMMAND=printf "\033]0;<mock-chroot>\007"
TERM=vt100
USER=root
SHLVL=1
PS1=<mock-chroot> \s-\v\$ 
DEBUGINFOD_URLS=https://debuginfod.fedoraproject.org/ 
PATH=/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin
MAIL=/var/spool/mail/root
_=/usr/bin/env

I found out that to reproduce, all I have to do is to set TERM=vt100. I don't know the actual meaning of that, but it changes the behavior of the new REPL, but not the old.

$ TERM=vt100 python3.13
Python 3.13.0rc2 (main, Sep  7 2024, 00:00:00) [GCC 13.3.1 20240522 (Red Hat 13.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 

Pressing either of Del, PgUp, or PgDn (possibly other keys?) adds a literal ~ instead of doing any of the expected actions (history traverse up, down, deleting the next character if any).

$ TERM=vt100 python3.12
Python 3.12.6 (main, Sep  9 2024, 00:00:00) [GCC 13.3.1 20240522 (Red Hat 13.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 

Pressing either of Del, PgUp, or PgDn does what it is supposed to do.

---

To reproduce my actual use case, first install mock. The easiest way is to use podman (or docker) with Fedora. Following https://rpm-software-management.github.io/mock/#mock-inside-podman-fedora-toolbox-or-docker-container

$ podman run --rm --privileged -ti fedora:40 bash  # or docker run --cap-add=SYS_ADMIN ...
# dnf install -y mock
# useradd mockbuilder
# usermod -a -G mock mockbuilder
# su - mockbuilder
$ mock -r fedora-rawhide-x86_64 --no-bootstrap-image install python3.13 python3.12
...
$ mock -r fedora-rawhide-x86_64 shell
...
<mock-chroot> sh-5.2# python3.13
Python 3.13.0rc2 (main, Sep  7 2024, 00:00:00) [GCC 14.2.1 20240905 (Red Hat 14.2.1-2)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

• gh-124027: Support Del, PgUp, and PgDn on TERM=vt100 #124028
• [3.13] gh-124027: Support Del, PgUp, and PgDn on TERM=vt100 (GH-124028) #124029

[hroncok]

I think this might be a ncurses thing. Trying to figure out which one... but it's getting late.

[hroncok]

Adding this keymap entry solves the delete case:

(r"\x1b[3~", "delete"),