I left the code in because it was harmless (a 100%-predictable branch), and it was easier to show that overflow was _considered_ than to explain in full why it was impossible.  In the context of CPython.  For example, the Java port of this code couldn't rely on the far-removed-from-this-code details of Python's C heap management (the largest Java signed integer is a legit Java array index), and signed integer overflow _is_ wholly defined in Java.  Which happens to be the same way it worked under virtually all C compilers at the time the code was written.  The idea that C compilers should be as aggressive as Fortran compilers instead of just supplying a portable assembly language is a modern conceit ;-)

The code is useless, but it's not "a bug", so I'm removing Python 2 from the list of targets.