Bug report

The simplest example, import Tkinter and create the root widget:

>>> import tkinter
>>> root = tkinter.Tk()
>>> █

A new Tk window appeared and grabbed the focus. Switch back to the terminal and press the <Up> key -- nothing changed:

>>> import tkinter
>>> root = tkinter.Tk()
>>> █

Press it again -- the last entered line appeared for editing:

>>> import tkinter
>>> root = tkinter.Tk()
>>> root = tkinter.Tk()█

Press the <Enter> key and the edited line will be replaced by another line which will execute:

>>> import tkinter
>>> root = tkinter.Tk()
>>> import tkinter
>>> █

cc @pablogsal