--- drupal-7.x-dev/includes/common.inc.orig	2009-02-17 07:49:13.000000000 +0000
+++ drupal-7.x-dev/includes/common.inc	2009-02-17 08:26:08.000000000 +0000
@@ -535,9 +535,18 @@
     // host that do not take into account the port number.
     'Host' => $host,
     'User-Agent' => 'Drupal (+http://drupal.org/)',
-    'Content-Length' => strlen($options['data']),
   );
 
+  // Only add 'Content-Length' if we actually have any content or if it is a
+  // POST or PUT request. Some non-standard servers get confused by content length
+  // in at least HEAD/GET requests, and Squid always requires content length in
+  // POST/PUT requests.
+  if (strlen($options['data']) ||
+      $options['method'] == "POST" ||
+      $options['method'] == "PUT") {
+    $options['headers']['Content-Length'] = strlen($options['data']);
+  }
+
   // If the server url has a user then attempt to use basic authentication
   if (isset($uri['user'])) {
     $options['headers']['Authorization'] = 'Basic ' . base64_encode($uri['user'] . (!empty($uri['pass']) ? ":" . $uri['pass'] : ''));