Python: Double KeyboardInterrupt in Windows?

I'm running a console-based app in Python 3.1.2. I want the app to trap a Ctrl-C at the prompt and handle it according to context. I'm getting the KeyboardInterrupt as expected, but unexpectedly, I'm sometimes seeing it again when I go to write a warning message. The tracebacks are below. Any thoughts from you smart people?

Traceback (most recent call last):
  File "E:\Dropbox\git\vocabulary\v.py", line 58, in main
    command, args = c.getcommand()
  File "E:\Dropbox\git\vocabulary\console.py", line 81, in getcommand
    command, *args = input(prompt).split()
KeyboardInterrupt

During 开发者_如何学Gohandling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "E:\Dropbox\git\vocabulary\v.py", line 125, in 
    main()
  File "E:\Dropbox\git\vocabulary\v.py", line 71, in main
    print("\nUse 'quit' to exit the application.")
  File "E:\Dropbox\git\vocabulary\utilities.py", line 191, in write
    self.stream.write(data)
KeyboardInterrupt

I can't reproduce this.

def foo():
    try:
        x = 0
        while True:
            x += 1        
    except KeyboardInterrupt:
        print(x)
while True:
    foo()

Works just fine and traps CTRL-C as expected.