fixed the nested test

Author: James Halliday

lib/results.js

@@ -61,7 +61,12 @@ Results.prototype.push = function (t, parentT) {
             }
         });
         self.push(st, t);
-        if (subtests === 1) st.run();
+        if (subtests === 1) {
+            if (plan === undefined) st.run();
+            else nextTick(function () {
+                st.run();
+            });
+        }
     });
 
     t.on('result', function (res) {