the current function definition reads:

function replaceBlockfile($block, $filename, $keep_content = false)
{
    return $this->replaceBlock($block, $this->getFile($filename));
} // end func replaceBlockfile

$keep_content is never passed on to replaceBlock(), the function should read:

function replaceBlockfile($block, $filename, $keep_content = false)
{
    return $this->replaceBlock($block, $this->getFile($filename), $keep_content);
} // end func replaceBlockfile