DrDaveHPP

Nope – turned out there was a problem with the en-GB translation. They had to pull the download file and rebuild it correctly (which they’ve now done). After that it’s simply a matter of editing the version number in /wp-includes/version.php and then updating from within the WP admin panel.

Edit: see discussion here – http://ww.wp.xz.cn/support/topic/accidentally-upgraded-to-40-alpha

Sorted it with a tweak to the /wp-includes/formatting.php file.

Adjust the end of existing Line 61:

... } elseif (strpos($curl, '<code') !== false || strpos($curl, '<kbd') !== false || strpos($curl, '<style') !== false || strpos($curl, '<script') !== false) {

so that it ends:

... || strpos($curl, '<script') !== false || strpos($curl, 'ript>') !== false || strpos($curl, '//') !== false) {

Other similar tweaks would no doubt cure other similar problems with overzealous reformatting.