Merge branch '4.3' into 4.4

* 4.3:
  gracefully handle missing event dispatchers
  [Cache] fix memory leak when using PhpArrayAdapter
  fix parsing negative octal numbers
  [SecurityBundle] Properly escape regex in AddSessionDomainConstraintPass
  [Config] never try loading failed classes twice with ClassExistenceResource

Author: nicolas-grekas

DependencyInjection/Compiler/AddSessionDomainConstraintPass.php

@@ -31,7 +31,7 @@ public function process(ContainerBuilder $container)
         }
 
         $sessionOptions = $container->getParameter('session.storage.options');
-        $domainRegexp = empty($sessionOptions['cookie_domain']) ? '%s' : sprintf('(?:%%s|(?:.+\.)?%s)', preg_quote(trim($sessionOptions['cookie_domain'], '.')));
+        $domainRegexp = empty($sessionOptions['cookie_domain']) ? '%%s' : sprintf('(?:%%%%s|(?:.+\.)?%s)', preg_quote(trim($sessionOptions['cookie_domain'], '.')));
 
         if ('auto' === ($sessionOptions['cookie_secure'] ?? null)) {
             $secureDomainRegexp = sprintf('{^https://%s$}i', $domainRegexp);