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If you press CTRL+c while Python is starting, you may get such error:
^CFatal Python error: Py_Initialize: can't initialize sys standard streams
Traceback (most recent call last):
 File "<frozen importlib._bootstrap>", line 990, in _find_and_load
 File "<frozen importlib._bootstrap>", line 571, in load_module
 File "<frozen importlib._bootstrap>", line 228, in module_for_loader_wrapper
 File "<frozen importlib._bootstrap>", line 456, in _load_module
 File "/home/haypo/prog/python/default/Lib/io.py", line 90, in <module>
 RawIOBase.register(FileIO)
 File "/home/haypo/prog/python/default/Lib/abc.py", line 155, in register
 if issubclass(subclass, cls):
 File "/home/haypo/prog/python/default/Lib/abc.py", line 201, in __subclasscheck__
 elif subclass in cls._abc_negative_cache:
KeyboardInterrupt
Abandon

OK, so what's your point? =) I mean you stopped the interpreter while in the middle of starting up. Do you want to trigger a fatal error if the exception raised was KeyboardInterrupt?

I think Victor's point was that you get the "can't initialize standard streams" in addition to the KeyboardInterrupt (but I'm just guessing).
(See issue 14228 for examples of what normally happens on a startup KeyboardInterrupt.)

> OK, so what's your point? =)
In Python < 3.3, CTRL+c at startup fails with "Traceback: ...", not
with a fatal error. A fatal error may dump a core dump and open a
popup on Windows.

Welcome to Python code running during startup. =) As I said, the only thing I can think of is raising the exception instead of catching it and immediately triggering the fatal exception, but that specific fatal error was not introduced by me so this is just a side-effect of having Python code running during startup.

Hmm, I've managed to produce the error with 3.1:
$ python3.1
Fatal Python error: Py_Initialize: can't initialize sys standard streams
Traceback (most recent call last):
 File "/usr/lib/python3.1/io.py", line 60, in <module>
 import _io
 File "/usr/lib/python3.1/os.py", line 380, in <module>
 from _abcoll import MutableMapping # Can't use collections (bootstrap)
 File "/usr/lib/python3.1/encodings/iso8859_15.py", line 14, in decode
 def decode(self,input,errors='strict'):
KeyboardInterrupt
Aborted

So importlib just increased the window of vulnerability for this kind of thing.

The funny thing is, in 3.3 I can't reproduce it (i.e. I only get
the KeyboardInterrupt). So I'm not sure if this happens more often
now.
^CTraceback (most recent call last):
 File "<frozen importlib._bootstrap>", line 989, in _find_and_load
 File "<frozen importlib._bootstrap>", line 571, in load_module
 File "<frozen importlib._bootstrap>", line 228, in module_for_loader_wrapper
 File "<frozen importlib._bootstrap>", line 456, in _load_module
 File "/home/stefan/pydev/cpython/Lib/site.py", line 537, in <module>
 main()
 [...]
 File "/home/stefan/pydev/cpython/Lib/collections/__init__.py", line 322, in namedtuple
 field_names = list(map(str, field_names))
KeyboardInterrupt

In a running interpreter and Idle, ^C results in
KeyboardInterrupt
>>> 
and nothing else.
From a command line, I think
KeyboardInterrupt: Python startup stopped"
<cli prompt>
would be ideal.
On Windows, I do not know if a program started from an icon, shortcut, or explorer *can* be interrupted, except possibly with Task Manager if the entry shows up fast enough, as it should not get keyboard focus until started.

> Hmm, I've managed to produce the error with 3.1:
Oh oh, I thought that importlib changed the behaviour, but I'm wrong. importlib doesn't change anything so I'm closing the issue as invalid.