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I've found a very strange bug in python 3.3
It's taken me around an hour just to narrow it down to a small case where it happens.
I cannot for the life of me figure out the exact cause. It seems to have something to do with "yield from".
I've attached a case which reproduces this. Run python3.3 test.py, it should segfault on linux, "stopped responding" on windows.
Tested with
OS: Linux Debian-60-squeeze-32-minimal 2.6.32-5-686-bigmem
PY: Python 3.3.1rc1 (default, Mar 30 2013, 21:44:39)
OS: Windows 7 64 bit
PY: Python 3.3.0 (v3.3.0:bd8afb90ebf2, Sep 29 2012, 10:55:48) [MSC v.1600 32 bit (Intel)] on win32
NOTES: If you get rid of "import logging" in generators.py, it only crashes if there's no __pycache__

The file contents so people dont have to download the zip:
generators.py:
---------------------------
def subgen():
	yield
def other_gen(self):
	move = yield from subgen()
game.py:
---------------------------
class Game(object):
	def __init__(self):
		self.gen = self.first_gen()
		next(self.gen)
	def first_gen(self):
		while True:
			from generators import \
				other_gen
			yield from other_gen(self)
test.py:
---------------------------
from game import Game
Game()

The crashing version has 'import logging' at the top of generators.py. I did not experience a crash when it was absent even if there was no __pycache__.
It also doesn't crash if the import is moved out of the body of first_gen.
FAULTHANDLER doesn't fair too well on this one, no real surprise :)
Fatal Python error: Segmentation fault
Current thread 0xb75856c0:
zsh: segmentation fault PYTHONFAULTHANDLER=true ../python test.py

This is the patch. I'll have to think about whether there's a self-contained way to test this.

New changeset 35cb75b9d653 by Benjamin Peterson in branch '3.3':
don't run frame if it has no stack (closes #17669)
http://hg.python.org/cpython/rev/35cb75b9d653
New changeset 0b2d4089180c by Benjamin Peterson in branch 'default':
merge 3.3 (#17669)
http://hg.python.org/cpython/rev/0b2d4089180c 

New changeset 516303f32bad by Benjamin Peterson in branch '3.3':
add a test for issue #17669 (closes #18565)
http://hg.python.org/cpython/rev/516303f32bad