url brocken / become /2F

I cannot reproduce:

PHP Code:

<?php

namespace App\Controllers;

class Home extends BaseController
{
    public function index()
    {
        helper('form');
        return form_open("/login/logincheck");
    }
} 


I see <form action="http://localhost:8080/index.php/login/logincheck" method="post" accept-charset="utf-8">

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