Description:
------------
At pear/install-pear-nozlib.phar for php 5.1.2 and at 
pear/PEAR/Config.php for php 4.4.2 there is the sequence:

// Default for php_dir
if (getenv('PHP_PEAR_INSTALL_DIR')) {
    define('PEAR_CONFIG_DEFAULT_PHP_DIR', 
getenv('PHP_PEAR_INSTALL_DIR'));
} else {
    if (@is_dir($PEAR_INSTALL_DIR)) {
        define('PEAR_CONFIG_DEFAULT_PHP_DIR',
               $PEAR_INSTALL_DIR);
    } else {
        define('PEAR_CONFIG_DEFAULT_PHP_DIR', 
$PEAR_INSTALL_DIR);
    }
}

Please note that the blocks controled by the if(@is_dir) 
are just the same. So either we wouldn't need the check, 
or the second block is mistyped.