rarely needed, but can sometimes be useful to release objects
referenced by the traceback held in sys.exc_info()[2]. (SF patch
#693195.) Thanks to Kevin Jacobs!
module. This increases code coverage of Python/sysmodule.c
from 68% to 77% (on Linux).
The script doesn't exercise the error branch that handles an evil
or lost sys.excepthook in Python/pythonrun.c::PyErr_PrintEx().
Also this script might not work on Jython in its current form.
From SF patch #662807.