MDL-46561 session: use full session validation in \core\session\manager::session_exists()

lib/classes/session/database.php

@@ -82,19 +82,16 @@ class database extends handler {
     }
 
     /**
-     * Check for existing session with id $sid.
+     * Check the backend contains data for this session id.
      *
-     * Note: this verifies the storage backend only, not the actual session records.
+     * Note: this is intended to be called from manager::session_exists() only.
      *
      * @param string $sid
      * @return bool true if session found.
      */
     public function session_exists($sid) {
-        try {
-            return $this->database->record_exists('sessions', array('sid'=>$sid, 'state'=>0));
-        } catch (\dml_exception $ex) {
-            return false;
-        }
+        // It was already checked in the calling code that the record in sessions table exists.
+        return true;
     }
 
     /**