Password changed via changePassword even if current password is incorrect

If I try to change a user's password, I run code like the below:

```
$api->user->changePassword(array(
                "new_password" => $new_password,
                "current_password" => $current_password,
                "user_id" => $user_id
```

However, if the value for $current_password is incorrect, the password is still changed.
