pfSsh.php playback script to change username

[regexaurus]

I have this working pfSsh.php playback script that takes a current/existing username and a new username as arguments and changes the existing username to the new username.

require_once("config.inc");
require_once("auth.inc");
require_once("functions.inc");

global $argv, $userindex;
$userindex = index_users();

$args = array_slice($argv, 3);

if (empty($args[0]) || empty($args[1])) {
        exit(-1);
} else {
	$oldusername = $args[0];
	$newusername = $args[1];
}
$oldusername = trim($oldusername);
$newusername = trim($newusername);

$user_item_config = getUserEntry($oldusername);
$user = &$user_item_config['item'];
if ($user == NULL) {
	exit(-1);
}

if ($oldusername !== $newusername) {
	config_set_path("/system/user/" . $userindex[$oldusername] . "/name", $newusername);
	write_config(sprintf(gettext("Username changed for user '%s' from console."), $oldusername));
	exit(0);
} else {
	exit(-1);
}

I started with the "built-in" changepassword script and tweaked it for my purposes. While my script to change usernames works, it doesn't change the user's home directory to the new username, and at first if I do something like pw usershow -n oldusername, I still see an entry for the old user. If I reboot, pw usershow -n oldusername returns 'no such user', but /home/oldusername still exists. /home/newusername exists as well. I'm wondering if there is a preferred/standard/idiomatic approach? I first tried the playback script below, thinking local_user_set() (found in /etc/inc/auth.inc) would handle a username change more thoroughly/properly, but had no success.

require_once("config.inc");
require_once("auth.inc");
require_once("functions.inc");

global $argv, $userindex;
$userindex = index_users();

$args = array_slice($argv, 3);

if (empty($args[0]) || empty($args[1])) {
        exit(-1);
} else {
	$oldusername = $args[0];
	$newusername = $args[1];
}
$oldusername = trim($oldusername);
$newusername = trim($newusername);

$user_item_config = getUserEntry($oldusername);
$user = &$user_item_config['item'];
if ($user == NULL) {
	exit(-1);
}

if ($oldusername !== $newusername) {
	$user['name'] = $newusername;
	local_user_set($user);
	write_config(sprintf(gettext("Username changed for user '%s' from console."), $oldusername));
	exit(0);
} else {
	exit(-1);
}

In this part of local_user_set(), I did confirm it uses the success branch (useradd), when I attempt to change a username:

/* determine add or mod */
        if (($userattrs[0] != $user['name']) || (!strncmp($pwread, "pw:", 3))) {
                $user_op = "useradd -m -k " . escapeshellarg($skel_dir) . " -o";
        } else {
                $user_op = "usermod";
        }

Not what I'm trying to achieve.
I also tried:

mv /home/oldusername /home/newusername
pw usermod -n oldusername -d /home/newusername -l newusername

But this seems to leave the system in an inconsistent state.
pw usershow -n oldusername
still shows an entry for the old/original username. Interestingly,
getent passwd
does not.