Merge branch 'agclever-count-use-handle-callback' it push origin 2.0nto 2.0

Author: christkv

lib/cursor.js

@@ -944,7 +944,9 @@ var count = function(self, applySkipLimit, opts, callback) {
     if(result.documents.length == 1
       && (result.documents[0].errmsg
       || result.documents[0].err
-      || result.documents[0]['$err'])) return callback(MongoError.create(result.documents[0]));
+      || result.documents[0]['$err'])) {
+      return handleCallback(callback, MongoError.create(result.documents[0]));
+    }
     handleCallback(callback, null, result.documents[0].n);
   });