app/code/community/Nexcessnet/Turpentine/Model/Observer/Esi.php
public function setReplaceFormKeyFlag($eventObject) {
        $esiHelper = Mage::helper('turpentine/esi');
        $varnishHelper = Mage::helper('turpentine/varnish');
        $request = Mage::app()->getRequest();
        if ($esiHelper->shouldResponseUseEsi() &&
                $varnishHelper->csrfFixupNeeded() &&
                ! $request->isPost()) {
            Mage::register('replace_form_key', true);
        }
    }
public function setReplaceFormKeyFlag($eventObject) {
        $esiHelper = Mage::helper('turpentine/esi');
        $varnishHelper = Mage::helper('turpentine/varnish');
        $request = Mage::app()->getRequest();
        if ($esiHelper->shouldResponseUseEsi() &&
                $varnishHelper->csrfFixupNeeded() &&
                ! $request->isPost()) {
            Mage::register('replace_form_key', true);
        }
    }
public function setReplaceFormKeyFlag ( $ eventObject ) { $ esiHelper = Mage :: helper ( 'turpentine/esi' ) ; $ varnishHelper = Mage :: helper ( 'turpentine/varnish' ) ; $ request = Mage :: app ( ) -> getRequest ( ) ; if ( $ esiHelper -> shouldResponseUseEsi ( ) && $ varnishHelper -> csrfFixupNeeded ( ) && ! $ request -> isPost ( ) ) { Mage :: register ( 'replace_form_key' , true ) ; } }
Check the magento version and runtime env and set the replace_form_key
flag if needed

@param Varien_Object $eventObject
@return null
Check the magento version and runtime env and set the replace_form_key flag if needed