ZF-6555: Variable $attrstring misspelled in HeadScript.php
The variable $attrstring is misspelled on line 412 (I'm using v1.8 but I think the same line was in the previous versions). It should be $attrString instead (capiral S).
// search for // $html = $indent . '
As a result of this misspelling a notice is displayed: Notice: Undefined variable: attrstring in /home/securedev/library/Zend/View/Helper/HeadScript.php on line 412