athena.py: fix interactive mode exit for Python 3.10+
Python >= 3.10 no longer silently ignores exceptions (e.g. SystemExit
raised by sys.exit
) in exit handlers (see cpython issue #103512). This fixes the error message seen when exiting athena -i
via Ctrl+D.
Also make sure to print the actual code passed to the exit()
function in case one was given.