Closed `sys.stdout` causes an endless stream of tracebacks in the repl

Bug report

Bug description:

Steps to reproduce:

Run Python 3.14.7 and enter the following:

import sys
f = open("file.txt", "w")
sys.stdout = f
f.close()

After the file is closed, the REPL attempts to display the next prompt.

Actual behavior:

The REPL repeatedly raises:

ValueError: I/O operation on closed file

This results in a very large stream of repeated tracebacks instead of returning to a usable prompt.
The traceback points to _pyrepl and eventually to:

_colorize.py", line 313, in can_colorize
    return os.isatty(file.fileno())
ValueError: I/O operation on closed file

Expected behavior:

The REPL should handle a closed sys.stdout gracefully instead of repeatedly emitting tracebacks.

Environment:

Python: 3.14.7
OS: Fedora Linux 44 (Workstation Edition) x86_64

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs

• gh-157590

まず、313行目付近の _colorize.py にある _pyrepl traceback と can_colorize エントリーポイントから始め、Python 3.14 REPL で sys.stdout が閉じられたケースを再現します。完了条件は、閉じられた stdout が無限に traceback を出力し続けなくなり、REPL が次の prompt を適切に処理することです。