http://www.python.org/dev/peps/pep-0342/
" 6. Allow "yield" to be used in try/finally blocks, since garbage
       collection or an explicit close() call would now allow the
       finally clause to execute."

"New syntax: yield allowed inside try-finally

    The syntax for generator functions is extended to allow a
    yield-statement inside a try-finally statement."


>>> def f():
...   try:
...     yield 1
...     yield 2
...     yield 3
...   finally:
...     yield 4
... 
>>> g = f()
>>> next(g)
1
>>> next(g)
2
>>> g = f()
Exception RuntimeError: 'generator ignored GeneratorExit' in <generator object f at 0xb74d2504> ignored
>>>