Evil code from Python standard library

Question

So, we had this: http://lucumr.pocoo.org/2009/3/1/the-1000-speedup-or-the-stdlib-sucks . This demonstrates a rather bad mistake, which probably costs the universe a load of cycles, even when we speak. Now it is fixed, and that's great.

So, which parts of the standard library have you noticed evil?

I expect all responsible people to respond with an error message (if appropriate) and a patch (if superman).

Answer 1

(since this is a different module, placing it in a different answer)

cgitb has some weird threading issues. See this bug report .

Answer 2

Never relate to malice, which can be adequately explained by stupidity.

Answer 3

The rexec module has so many security holes that it is almost useless.