title: XML Parsing Error: SYSTEM or PUBLIC, the URI is missing
body: <p>I am parsing an RSS feed from the following URL:</p>
  
  <p><a href="http://rss.sciam.com/ScientificAmerican-Global?format=xml" rel="nofollow noreferrer">http://rss.sciam.com/ScientificAmerican-Global?format=xml</a></p>
  
  <pre><code>// $xml_text is filled with the contents read from the URL
  $xml_parser = xml_parser_create();
  $res = xml_parse($xml_parser, $xml_text);
  
  if (!$res) {
    $error =
      xml_error_string(xml_get_error_code($xml_parser)).
      " at line ".
      xml_get_current_line_number($xml_parser);
  }
  
  // $error contains: "SYSTEM or PUBLIC, the URI is missing at line 1"
  </code></pre>
  
  <p><a href="http://FeedValidator.org" rel="nofollow noreferrer">FeedValidator.org</a> says this is a good feed.</p>
  
  <p>How can I get PHP's XML parser to work around this error?</p>
  
  <p><strong>EDIT</strong>: It looks like they are redirecting this feed to another location based on the user-agent.  My PHP script is not getting the correct feed.</p>