Fix atexit unraisable exception message format by youknowone · Pull Request #7399 · RustPython/RustPython

* Fix atexit unraisable exception message format

Match PyErr_FormatUnraisable behavior: use
"Exception ignored in atexit callback {func!r}" as err_msg
and pass None as object instead of the callback function.

* Fix atexit unregister deadlock with reentrant __eq__

Release the lock during equality comparison in unregister so
that __eq__ can safely call atexit.unregister or atexit._clear.
Store callbacks in LIFO order (insert at front) and use
identity-based search after comparison to handle list mutations,
matching atexitmodule.c behavior.

Also pass None as err_msg when func.repr() fails, matching
CPython's PyErr_FormatUnraisable fallback.

* Fix atexit unraisable exception message format

Match PyErr_FormatUnraisable behavior: use
"Exception ignored in atexit callback {func!r}" as err_msg
and pass None as object instead of the callback function.

* Fix atexit unregister deadlock with reentrant __eq__

Release the lock during equality comparison in unregister so
that __eq__ can safely call atexit.unregister or atexit._clear.
Store callbacks in LIFO order (insert at front) and use
identity-based search after comparison to handle list mutations,
matching atexitmodule.c behavior.

Also pass None as err_msg when func.repr() fails, matching
CPython's PyErr_FormatUnraisable fallback.