This bug was previously reported in
http://bugs.python.org/issue3180
but was closed after seven years for being out of date.
Still, the bug remains: Interrupts are lost during readline PyOS_InputHook processing.

To reproduce the bug, try

>>> from Tkinter import *
>>> Tk()

You will notice that Ctrl-C now does not generate a KeybordInterrupt.

This bug appears in all Python versions I tested (Python 2.7, 3.3, 3.4) and, judging from the source code, is still present in the current Python source code in Mercurial. The bug appears both on Mac and on Linux; I do not have access to Windows.

The suggested patch at http://bugs.python.org/issue3180 makes multiple changes to the behavior of PyOS_InputHook. In particular, it allows for waiting for a file descriptor other than stdin. I think that this is unrelated to the current bug, so it should not be included in the patch, in particular since that would change the API.