Allow reuse of Session between requests

Author: tgalopin

src/Symfony/Component/HttpFoundation/Session/Session.php

@@ -178,7 +178,9 @@ public function getId()
      */
     public function setId($id)
     {
-        $this->storage->setId($id);
+        if ($this->storage->getId() !== $id) {
+            $this->storage->setId($id);
+        }
     }
 
     /**

src/Symfony/Component/HttpFoundation/Tests/Session/SessionTest.php

@@ -70,6 +70,27 @@ public function testSetId()
         $this->assertEquals('0123456789abcdef', $this->session->getId());
     }
 
+    public function testSetIdAfterStart()
+    {
+        $this->session->start();
+        $id = $this->session->getId();
+
+        $e = null;
+        try {
+            $this->session->setId($id);
+        } catch (\Exception $e) {
+        }
+
+        $this->assertNull($e);
+
+        try {
+            $this->session->setId('different');
+        } catch (\Exception $e) {
+        }
+
+        $this->assertInstanceOf('\LogicException', $e);
+    }
+
     public function testSetName()
     {
         $this->assertEquals('MOCKSESSID', $this->session->getName());

src/Symfony/Component/HttpFoundation/Tests/Session/Storage/MockArraySessionStorageTest.php

@@ -48,7 +48,7 @@ protected function setUp()
         $this->data = array(
             $this->attributes->getStorageKey() => array('foo' => 'bar'),
             $this->flashes->getStorageKey() => array('notice' => 'hello'),
-            );
+        );
 
         $this->storage = new MockArraySessionStorage();
         $this->storage->registerBag($this->flashes);