merge in multisite login, wp-includes, See #11644

git-svn-id: https://develop.svn.wordpress.org/trunk@12697 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/capabilities.php

@@ -987,6 +987,9 @@ function map_meta_cap( $cap, $user_id ) {
 function current_user_can( $capability ) {
 	$current_user = wp_get_current_user();
 
+        if( is_multisite() && is_super_admin() )
+                return true;
+
 	if ( empty( $current_user ) )
 		return false;