The template for the PHP question type seems to be broken. I'll look into how and when this happened but for now the fix is to edit the built-in prototype for the PHP question type (that is, the question called "BUILT_IN_PROTOTYPE_php" in the System > CR_Prototypes category) , replacing the line
define('SEPARATOR', '#<ab@17943918#@>#');with
define('SEPARATOR', "#<ab@17943918#@>#\n");Sorry about the bug; thanks for reporting it.
Richard