Python 3.13.0b1 REPL sometimes swallows the output

[hroncok]

Bug report

Bug description:

I was debugging a certain issue in setuptools tests in Python 3.13.0b1 REPL:

>>> import os, posixpath
>>> path = r'\foo/bar.txt'
>>> os.path.pardir in path.split(posixpath.sep)
(no output)

I was worried. Shouldn't the result be True or False exclusively?

>>> os.path.pardir in path.split(posixpath.sep)
>>> os.path.pardir in path.split(posixpath.sep)
False
>>> os.path.pardir in path.split(posixpath.sep)
False
>>> os.path.pardir in path.split(posixpath.sep)
False
>>> os.path.pardir in path.split(posixpath.sep)
False
>>> os.path.pardir in path.split(posixpath.sep)
False

Huh? Let's try again with something simpler:

>>> 'a' in 'aaa'
>>> 'a' in 'aaa'
True

This appears to happen entirely at random for me.

$ python3.13
Python 3.13.0b1 (main, May  9 2024, 00:00:00) [GCC 14.1.1 20240507 (Red Hat 14.1.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 'a' in 'aaa'
>>> 'a' in 'aaa'
True

$ python3.13
Python 3.13.0b1 (main, May  9 2024, 00:00:00) [GCC 14.1.1 20240507 (Red Hat 14.1.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 'a' in 'aaa'
True
>>> 'a' in 'aaa'
True

This is on Fedora Linux 39.

python3.13-3.13.0~b1-2.fc41.x86_64
readline-8.2-6.fc39.x86_64
ncurses-libs-6.4-7.20230520.fc39.1.x86_64

CPython versions tested on:

3.13

Operating systems tested on:

Linux

[hugovk]

Did you paste the lines with swallowed output? If so, see #118893.

[hroncok]

Thanks. I did, but I did not notice that as I was mixing pasting,t typing and using the prompt history.

This is a duplicate of #118893.