MDL-34290 Allow to have several requests to the same instance of oauth_helper

lib/filelib.php

@@ -2898,6 +2898,13 @@ class curl {
         unset($this->options['CURLOPT_FILE']);
     }
 
+    /**
+     * Resets the HTTP Request headers (to prepare for the new request)
+     */
+    public function resetHeader() {
+        $this->header = array();
+    }
+
     /**
      * Set HTTP Request Header
      *

lib/oauthlib.php

@@ -289,6 +289,9 @@ class oauth_helper {
         $oauth_params = $this->prepare_oauth_parameters($url, array('oauth_token'=>$token), $method);
         $this->setup_oauth_http_header($oauth_params);
         $content = call_user_func_array(array($this->http, strtolower($method)), array($url, $params, $this->http_options));
+        // reset http header and options to prepare for the next request
+        $this->http->resetHeader();
+        // return request return value
         return $content;
     }