TYPO3 Core

<f:if condition="'{v:variable.register.get(name: \'print\')}'">
    ...
</f:if>

was parsed as follow in the cache file

// Rendering Boolean node
// Rendering Array
$array23 = array();
$array23['0'] = '\'{v:variable.register.get(name: \\\'print\\\')}\'';

$expression24 = function($context) {return '{v:variable.register.get(name: \'print\';};
$arguments7['condition'] = TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\BooleanNode::convertToBoolean(
                                        $expression24(
                                                TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\BooleanNode::gatherContext($renderingContext, $array23)
                                        ),
                                        $renderingContext
                                );      

The condition was not fetched completely in the $expression24 line.