MDL-39461 badges: Fix cURL expectation failed error when trying to connect to backpack

badges/lib/backpacklib.php

@@ -60,10 +60,11 @@ class OpenBadgesBackpackHandler {
         }
 
         $options = array(
-            'FRESH_CONNECT' => true,
+            'FRESH_CONNECT'  => true,
             'RETURNTRANSFER' => true,
-            'FORBID_REUSE' => true,
-            'HEADER' => 0,
+            'FORBID_REUSE'   => true,
+            'HEADER'         => 0,
+            'HTTPHEADER'     => array('Expect:'),
             'CONNECTTIMEOUT' => 3,
         );