Issue #1862538 by Berdir: Convert drupal_http_request() usage in update.fetch.inc to Guzzle.

core/modules/update/update.fetch.inc

@@ -5,6 +5,8 @@
  * Code required only when fetching information about available updates.
  */
 
+use Guzzle\Http\Exception\RequestException;
+
 /**
  * Page callback: Checks for updates and displays the update status report.
  *
@@ -149,12 +151,14 @@ function _update_process_fetch_task($project) {
   $project_name = $project['name'];
 
   if (empty($fail[$fetch_url_base]) || $fail[$fetch_url_base] < $max_fetch_attempts) {
-    $result = drupal_http_request($url, array('headers' => array('accept' => 'text/xml')));
-    if (isset($result->error)) {
-      watchdog('update', 'HTTP request to @url failed with error: @error.', array('@url' => $url, '@error' => $result->error));
+    try {
+      $data = Drupal::httpClient()
+        ->get($url, array('Accept' => 'text/xml'))
+        ->send()
+        ->getBody(TRUE);
     }
-    elseif (!isset($result->error) && isset($result->data)) {
-      $data = $result->data;
+    catch (RequestException $exception) {
+      watchdog_exception('update', $exception);
     }
   }