bug #5513 [load_balancer_reverse_proxy ] Always use 127.0.0.1 as a trusted proxy (ruudk)

This PR was submitted for the 2.7 branch but it was merged into the 2.3 branch instead (closes #5513).

Discussion
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[load_balancer_reverse_proxy ] Always use 127.0.0.1 as a trusted proxy

Apparently the behaviour changed in Symfony 2.7. Before, the solution just worked perfectly with a Amazon ELB. After upgrading to Symfony 2.7 the subrequests weren't trusted anymore because they set the `REMOTE_ADDR` to `127.0.0.1`

Commits
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9b2c9f4 Always use 127.0.0.1 as a trusted proxy

Author: wouterj

cookbook/request/load_balancer_reverse_proxy.rst

@@ -83,7 +83,7 @@ In this case, you'll need to - *very carefully* - trust *all* proxies.
        // web/app.php
 
        // ...
-       Request::setTrustedProxies(array($request->server->get('REMOTE_ADDR')));
+       Request::setTrustedProxies(array('127.0.0.1', $request->server->get('REMOTE_ADDR')));
 
        $response = $kernel->handle($request);
        // ...