Description:
------------
calling `file_get_contents` through a configured proxy to an ssl site will let the certificate check "lag" one behind.

with the first call of the `file_get_contents` the certificate for the requested site will be "locked in" for the next call. which will therefor fail.

so only the first call of `file_get_contents` will be successful, the rest will fail.

Test script:
---------------
<?php
$stream_default_opts = [
  'http' => [
    'proxy'=>"tcp://5.9.78.28:3128",
    'request_fulluri' => true,
  ]
];
stream_context_set_default($stream_default_opts);
file_get_contents("https://www.symfony.com", false); 
file_get_contents("https://getcomposer.org", false); 
file_get_contents("https://github.com", false); 

Actual result:
--------------
Warning: file_get_contents(): Peer certificate CN=`getcomposer.org' did not match expected CN=`www.symfony.com' in foo.php on line 11
Warning: file_get_contents(https://getcomposer.org): failed to open stream: Cannot connect to HTTPS server through proxy in foo.php on line 11

Warning: file_get_contents(): Peer certificate CN=`github.com' did not match expected CN=`www.symfony.com' in foo.php on line 12
Warning: file_get_contents(https://github.com): failed to open stream: Cannot connect to HTTPS server through proxy in foo.php on line 12