Speaking about backward incompatible change, we'd like to move to Python 2.5 as the minimum required version of Python, mainly for being able to use the 'with' keyword. Most Linux distributions ship Python 2.6 since some time already and Python 2.7 final will be out soon, so we're in line with our usual practice of supporting the last 3 stable versions of Python.
I (more or less) maintain the trac package for pkgsrc, the standard packaging system on NetBSD and Dragonfly, and also available on Solaris, Linux, other BSDs (+ AIX, IRIX, HP-UX). pkgsrc tends to be a bit conservative about keeping old versions, but we now have 2.4, 2.5 and 2.6, with 2.6 default since September 2009. So dropping 2.4 support is totally fine with the pkgsrc world.
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