Fix error session already started (#14914)

* Fix error session already started

Got this error when going on eg  `index.php?module=PrivacyManager&action=privacySettings&idSite=1&period=week&date=2019-09-20` and a session was started by another tool. That page uses NONCE which then uses SessionNamespace which then wants to start the session even though it was already started.
I don't think I can write a test for it but need to see.

* add test

1 files changed, 7 insertions, 0 deletions

diff --git a/libs/Zend/Session.php b/libs/Zend/Session.php
index 8b55a17b6d..38c8a1ba86 100644
--- a/libs/Zend/Session.php
+++ b/libs/Zend/Session.php
@@ -424,6 +424,13 @@ class Zend_Session extends Zend_Session_Abstract
             return; // already started
         }
 
+        if (session_status() === PHP_SESSION_ACTIVE) {
+	        parent::$_readable = true;
+	        parent::$_writable = true;
+	        self::$_sessionStarted = true;
+	        return;
+        }
+
         // make sure our default options (at the least) have been set
         if (!self::$_defaultOptionsSet) {
             self::setOptions(is_array($options) ? $options : array());