[HttpFoundation] don't prefix cookies with "Set-Cookie:"

See symfony/symfony#25393

src/Symfony/Component/HttpFoundation/Session/Storage/Handler/AbstractSessionHandler.php

@@ -156,7 +156,7 @@ abstract class AbstractSessionHandler implements \SessionHandlerInterface, \Sess
             if ($sessionCookieFound) {
                 header_remove('Set-Cookie');
                 foreach ($otherCookies as $h) {
-                    header('Set-Cookie:'.$h, false);
+                    header($h, false);
                 }
             } else {
                 setcookie($this->sessionName, '', 0, ini_get('session.cookie_path'), ini_get('session.cookie_domain'), ini_get('session.cookie_secure'), ini_get('session.cookie_httponly'));

src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Handler/Fixtures/with_cookie_and_session.expected

@@ -0,0 +1,24 @@
+open
+validateId
+read
+doRead: abc|i:123;
+read
+updateTimestamp
+close
+open
+validateId
+read
+doRead: abc|i:123;
+read
+
+write
+destroy
+doDestroy
+close
+Array
+(
+    [0] => Content-Type: text/plain; charset=utf-8
+    [1] => Cache-Control: max-age=10800, private, must-revalidate
+    [2] => Set-Cookie: abc=def
+)
+shutdown

src/Symfony/Component/HttpFoundation/Tests/Session/Storage/Handler/Fixtures/with_cookie_and_session.php

@@ -0,0 +1,13 @@
+<?php
+
+require __DIR__.'/common.inc';
+
+setcookie('abc', 'def');
+
+session_set_save_handler(new TestSessionHandler('abc|i:123;'), false);
+session_start();
+session_write_close();
+session_start();
+
+$_SESSION['abc'] = 234;
+unset($_SESSION['abc']);