Loop on button on dual login

[neeesn]

Describe the bug
When dual login is set and we go to the login screen. The button sends us to sitename.com/login/index.php?saml=on but it doesnt "call" the login. we just go in loop.

To Reproduce
Steps to reproduce the behavior:
Install newest version in moodle 3.6.3
Set to dual login
Log out
Try and login via click the button

Desktop (please complete the following information):
Any browser

To make it work we changed the code in the loginpage_hook in auth.php line 198 - 228 :
From: /**
* @global string $SESSION
* @return type
*/
public function loginpage_hook() {
global $SESSION, $CFG;
$saml = optional_param('saml', 'undefined', PARAM_TEXT);
// If saml=off, go to default login page regardless any other
// settings. Useful to administrators to recover from misconfiguration
if ($saml == 'off') {
$SESSION->saml = 'off';
return;
}
// If dual login is disabled or saml=on, the user is redirect to the IdP
if ($saml == 'on') {
$SESSION->saml='on';
$this->saml2_login();
}
// Otherwise, is checked the last option in session
if (!empty($SESSION->saml) && $SESSION->saml == 'off') {
return;
}
if ($this->config->dual_login) {
return;
}
$this->saml2_login();
}

To this :

/**
* @global string $SESSION
* @return type
*/
public function loginpage_hook() {

    global $SESSION;

    if(!isset($SESSION->saml)){
        $SESSION->saml = '';
    }

    $saml = optional_param('saml', $SESSION->saml, PARAM_TEXT);

    /**
     * Check if dual login is enabled.
     * Can bypass IdP auth.
     * To bypass IdP auth, go to <moodle-url>/login/index.php?saml=off
     *
     */
    if ((int) $this->config->dual_login && $saml !== 'on') {
        $saml = 'off';
    }

    $SESSION->saml = !empty($saml) ? $saml : 'on';
    if (isset($SESSION->saml) && $SESSION->saml === 'off') {
        return;
    }

    $this->saml2_login();

}

[mfprimo]

Hi Henrik,
could you do a pull request?

[mfprimo]

Hi Henrik,
I was not able to reproduce the bug, but I trust you and applied your suggestion in the code.
Could you confirm new version works?