Weird behaviour with tmux send-keys

Bug report

Bug description:

Hi,

I'm experiencing some weird behaviour only in python 3.13, up to 3.12, this bug never appeared. I'm gonna try to explain it in the best possible way..

I use tmux send-keys to send a couple lines to my python prompt, to run a script from within the python interpreter, clear vars, change the working directory, etc. Now, in python 3.13, after a couple times of sending text to the python prompt this way, some weird behaviour happens.

I'm gonna make a simple example, let's say i send the text (again, using tmux send-keys function) to my python (3.13) prompt:

a = 3\u000D

Which would be a var definition + Enter, if i open a pytho nprompt and do that, it works perfect, now, after a while of sending text this way, when i do it again, the line doesn't get executed, in the prompt "appears" the first char in the line that i sent (in this example, "a"), and it the prompt gets like "paused". If i press any key on it, the line goes through. and it works normally.

This only happens to me in 3.13, i'm not sure if it's a tmux or python issue, my guess is python.

Any idea what could this be, or has anyone experienced something similar?

Thanks in advance !

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Reproduce the behavior in the Python 3.13 prompt on Linux using tmux send-keys, then compare it with Python 3.12 and determine whether tmux or Python is responsible. Confirm the issue with a minimal repeatable sequence and document what change or test would demonstrate that the prompt no longer pauses.