[IronPython] -i option doesn't go interactive when exception is raised

[Sanghyeon Seo]

One use of -i option is to inspect stack trace when exception is raised.

# test.py
1/0

$ python -i test.py
...
ZeroDivisionError
>>>

This way one can inspect variables at the time exception was raised.
Sure, debuggers can do that, but simple -i option is sometimes handy.

IronPython implements -i option, but it doesn't go interactive when
exception is raised.

Seo Sanghyeon