This switches the main pyrepl event loop to always be non-blocking so that it
can listen to incoming interruptions from other threads.
This also resolves invalid display of exceptions from other threads
(gh-123178).
This also fixes freezes with pasting and an active input hook.
(cherry picked from commit 033510e11d)
Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Miss Islington (bot)