Add __isset() to CI_Session
diff --git a/system/libraries/Session/Session.php b/system/libraries/Session/Session.php
index 77c56ae..c9d2e8a 100644
--- a/system/libraries/Session/Session.php
+++ b/system/libraries/Session/Session.php
@@ -584,6 +584,24 @@
// ------------------------------------------------------------------------
/**
+ * __isset()
+ *
+ * @param string $key 'session_id' or a session data key
+ * @return bool
+ */
+ public function __isset($key)
+ {
+ if ($key === 'session_id')
+ {
+ return (session_status() === PHP_SESSION_ACTIVE);
+ }
+
+ return isset($_SESSION[$key]);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
* __set()
*
* @param string $key Session data key