However, a 3 second clip used for testing purposes in an open source programming language appears to meet the guidelines for fair use in the United States. In particular, no one is going to use the test clip as a substitute for any part of the Monty Python skit. There is no trading on the content of the clip to capture any value whatsoever; it could be a test beep and it would serve the same purpose. In short, I think this could go on under fair use principles until there was some sort of complaint. 

That said, the content of the sound file really doesn't matter in this instance. It could be replaced by a clip of Barry saying "My hovercraft is full of eels" and the same functionality would be preserved.