Change record status: 
Project: 
Introduced in branch: 
8.x
Introduced in version: 
8.0-alpha2-dev
Description: 

The Guzzle library has been updated to version 3.7.

One of the relevant changes is how the final location is accessed after a redirect.

Before

<?php
// Update the feed URL in case of a 301 redirect.
if ($previous_response = $response->getPreviousResponse()) {
  if (
$previous_response->getStatusCode() == 301 && $location = $previous_response->getLocation()) {
   
$feed->url->value = $location;
  }
}
?>

After

<?php
// Update the feed URL in case of a 301 redirect.
if ($response->getEffectiveUrl() != $feed->url->value) {
 
$feed->url->value = $response->getEffectiveUrl();
}
?>

Another example, when using Last-Modified or similar headers in the Request, the response now needs to be checked for a HTTP 304 Not Modified explicitly and handled accordingly.

<?php
// Given code like this.
$request->addHeader('If-None-Match', $feed->etag->value);
$request->addHeader('If-Modified-Since', gmdate(DATE_RFC1123, $feed->modified->value));

// The status code now needs to be checked for 304 and handled.
if ($response->getStatusCode() == 304) {
  return
FALSE;
}
?>

See the the official upgrading documentation for all changes: UPGRADING.md

Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done