Merge branch '2.1' into 2.2

* 2.1:
  added support for the X-Forwarded-For header (closes #6982, closes #7000)
  fixed the IP address in HttpCache when calling the backend
  [EventDispatcher] Added assertion.
  [EventDispathcer] Fix removeListener
  [DependencyInjection] Add clone for resources which were introduced in 2.1
  [DependencyInjection] Allow frozen containers to be dumped to graphviz
  Fix 'undefined index' error, when entering scope recursively
  [Security] fixed session creation on login (closes #7011)
  Add dot character `.` to legal mime subtype regular expression
  [HttpFoundation] fixed the creation of sub-requests under some circumstancies (closes #6923, closes #6936)

1 files changed, 4 insertions, 2 deletions

diff --git a/Http/Firewall/ContextListener.php b/Http/Firewall/ContextListener.php
index 6c06ca8..8c71876 100644
--- a/Http/Firewall/ContextListener.php
+++ b/Http/Firewall/ContextListener.php
@@ -117,14 +117,16 @@ class ContextListener implements ListenerInterface
         }
 
         $request = $event->getRequest();
-        $session = $request->hasPreviousSession() ? $request->getSession() : null;
+        $session = $request->getSession();
 
         if (null === $session) {
             return;
         }
 
         if ((null === $token = $this->context->getToken()) || ($token instanceof AnonymousToken)) {
-            $session->remove('_security_'.$this->contextKey);
+            if ($request->hasPreviousSession()) {
+                $session->remove('_security_'.$this->contextKey);
+            }
         } else {
             $session->set('_security_'.$this->contextKey, serialize($token));
         }