src/PEAR/PackageFile/v2.php
function installedFile($file, $atts)
    {
        if (isset($this->_packageInfo['filelist'][$file])) {
            $this->_packageInfo['filelist'][$file] =
                array_merge($this->_packageInfo['filelist'][$file], $atts['attribs']);
        } else {
            $this->_packageInfo['filelist'][$file] = $atts['attribs'];
        }
    }
function installedFile($file, $atts)
    {
        if (isset($this->_packageInfo['filelist'][$file])) {
            $this->_packageInfo['filelist'][$file] =
                array_merge($this->_packageInfo['filelist'][$file], $atts['attribs']);
        } else {
            $this->_packageInfo['filelist'][$file] = $atts['attribs'];
        }
    }
This is only used at install-time, after all serialization
is over.