Fix scope of $noblogs_master variable

wp-nginx-map.php

@@ -35,6 +35,7 @@ function backend_to_http_endpoint($backend) {
 // Print the blog -> backend map.
 function generate_map() {
   global $wpdb;
+  global $noblogs_master;
   $wpdb_hash = &$wpdb->hash_map;
 
   $blogs = get_blogs();
@@ -54,4 +55,3 @@ function generate_map() {
 
 
 generate_map();
-