The function scorm_eval_prerequisites() uses the evil PHP eval() function. We should convert that to using the evalMath() class already included in Moodle which performs a similar task without being "evil"
the problematic code:
return eval('return '.implode($stack).';');
Most packages I have only have a single prereq item so $stack only contains a single item with the string ' true ' or ' false ' and in this case all that is really needed is:
instead of that other crap.
but... if there are multiple items $stack would contain something like this: (I don't have any packages to test this)
 => false
 => true
(the code puts 2 spaces before and after each value in the array (' false ', ' true ')