pyrepl messed up terminal if a signal handler expects stdin

Bug report

Bug description:

This is related to #129614 but more straightforward and irrelevant to pdb. (pdb needs this to be fixed though)

Start REPL from a terminal and do

import signal
signal.signal(signal.SIGINT, lambda s, f: input("test"))
<Ctrl+C>

Your terminal is messed up and newline won't work anymore. (Not the Python repl which will exit due to some run time error, the terminal itself is messed up)

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-138617

先在 Linux 上的 pyrepl REPL 中重現訊號處理程式和輸入序列，然後檢查 Ctrl+C 和 stdin 周邊的終端狀態處理。查看連結的 PR #138617，了解已在進行中的工作。當處理程式呼叫 input() 後，終端仍可使用並接受換行時，即表示完成。