We've gotten to the point where it's difficult to support Python 2.3 as
it's no longer readily available on many platforms. Python 2.3 was
released in July 2003, Python 2.4 was released in December 2004.
Mercurial 0.1 was released in April 2005. The target date for Mercurial
1.3 is July 1, 2009.
(please don't ask about deprecating 2.4 until about 2011)