Fix so SPECIAL-USE assignments are forced only until user sets special folders (#4782)

The old behaviour where SPECIAL-USE has always a prio can be bringed back
by setting lock_special_folders=false and adding it to dont_override.

CHANGELOG

@@ -30,6 +30,7 @@ CHANGELOG Roundcube Webmail
 - Protect download urls against CSRF using unique request tokens (#1490642)
 - newmail_notifier: Refactor desktop notifications
 - Fix so contactlist_fields option can be set via config file
+- Fix so SPECIAL-USE assignments are forced only until user sets special folders (#4782)
 
 RELEASE 1.2-beta
 ----------------

program/lib/Roundcube/rcube_imap.php

@@ -3304,6 +3304,12 @@ class rcube_imap extends rcube_storage
     public function get_special_folders($forced = false)
     {
         $result = parent::get_special_folders();
+        $rcube  = rcube::get_instance();
+
+        // Lock SPECIAL-USE after user preferences change (#4782)
+        if ($rcube->config->get('lock_special_folders')) {
+            return $result;
+        }
 
         if (isset($this->icache['special-use'])) {
             return array_merge($result, $this->icache['special-use']);

program/steps/settings/save_prefs.inc

@@ -124,6 +124,8 @@ case 'server':
 case 'folders':
     $a_user_prefs = array(
         'show_real_foldernames' => isset($_POST['_show_real_foldernames']) ? true : false,
+        // stop using SPECIAL-USE (#4782)
+        'lock_special_folders'  => !in_array('lock_special_folders', (array) $CONFIG['dont_override']),
     );
 
     foreach (rcube_storage::$folder_types as $type) {