Bug 1814316: Checking memcached version if stats not available

behatnotneeded

Change-Id: I2bc1172044a160d72905bf56a55f505ccd1250c0
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
(cherry picked from commit 650fae55)

htdocs/auth/session.php

@@ -112,7 +112,10 @@ class Session {
                         $server_stats = $memcached->getStats();
                         if ($server_stats[$destination . ":" . $port]['pid'] <= 0) {
                             // can't reach the destination:port
-                            throw new ConfigSanityException(get_string('nomemcachedserver', 'error', $server));
+                            $server_version = $memcached->getVersion();
+                            if (empty($server_version[$destination . ":" . $port])) {
+                                throw new ConfigSanityException(get_string('nomemcachedserver', 'error', $server));
+                            }
                         }
                     }
                     else {