#108663: Fix edge case for cookie domains (conform to RFC 2109)

sites/default/settings.php

@@ -142,8 +142,12 @@ ini_set('url_rewriter.tags',        '');
  */
 if (isset($_SERVER['HTTP_HOST'])) {
   $domain = '.'. preg_replace('`^www.`', '', $_SERVER['HTTP_HOST']);
+  // Per RFC 2109, cookie domains must contain at least one dot other than the
+  // first. For hosts such as 'localhost', we don't set a cookie domain.
+  if (count(explode('.', $domain)) > 2) {
     ini_set('session.cookie_domain', $domain);
   }
+}
 
 /**
  * Variable overrides: