Index: wp-includes/http.php
===================================================================
--- wp-includes/http.php	(revision 11524)
+++ wp-includes/http.php	(working copy)
@@ -625,6 +625,11 @@
 			}
 		}
 
+		//fsockopen has issues with 'localhost' with IPv6 with certain versions of PHP, It attempts to connect to ::1,
+		// which fails when the server is not setup for it. For compatibility, always connect to the IPv4 address.
+		if ( 'localhost' == strtolower($fsockopen_host) )
+			$fsockopen_host = '127.0.0.1';
+
 		// There are issues with the HTTPS and SSL protocols that cause errors that can be safely
 		// ignored and should be ignored.
 		if ( true === $secure_transport )