finally now the restore should work and with correct unicode related coding style, sorry

backup/lib.php

@@ -473,6 +473,8 @@
     //This function is used to add slashes (and decode from UTF-8 if needed)
     //It's used intensivelly when restoring modules and saving them in db
     function backup_todb ($data) {
+        global $CFG;
+
         if (empty($CFG->unicodedb)) {
             return restore_decode_absolute_links(addslashes(utf8_decode($data)));
         } else {

backup/restorelib.php

@@ -2920,7 +2920,9 @@
         //This function is used to get the current contents property value
         //They are trimed (and converted from utf8 if needed)
         function getContents() {
-            if (current_charset() != 'UTF-8') {
+            global $CFG;
+
+            if (empty($CFG->unicodedb)) {
                 return trim(utf8_decode($this->content));
             } else {
                 return trim($this->content);