Where did you see 1.5 listed as experimental? The front page clearly has 1.5.5 as the release and that takes you to a page that has 1.5.5 listed as the latest

Where did you see 1.5 listed as experimental? The front page clearly has 1.5.5 as the release and that takes you to a page that has 1.5.5 listed as the latest official version and 1.6 as the development version. Are you referring to 1.5's Python 3 support? That is experimental, but 1.5.5 itself is not.