test.only should not run any other test blocks

Previously test.only would run every test block but only output
the TAP result of the the one marked as only.

Now it won't run every function.

This is useful for wanting to run just one `test()` block in a
file for debugging / printing / performance / noise purposes.

lib/results.js

@@ -19,7 +19,7 @@ module.exports = function () {
     };
 
     nextTick(function next () {
-        var t = results.tests.shift();
+        var t = getNextTest(results);
         if (!t && results.running) return;
         if (!t) return results.close();
         t.run();
@@ -42,7 +42,7 @@ Results.prototype.push = function (t, parentT) {
     var write = function (s) { self.stream.queue(s) };
     t.once('prerun', function () {
         if (self.only && self.only !== t.name && !parentT) {
-            var nt = self.tests.shift();
+            var nt = getNextTest(self);
             if (nt) nt.run()
             else self.close();
             return;
@@ -94,7 +94,7 @@ Results.prototype.push = function (t, parentT) {
 
     t.once('end', function () {
         if (t._skip) {
-            var nt = self.tests.shift();
+            var nt = getNextTest(self);
             if (nt) nt.run();
             else self.close();
             return;
@@ -104,8 +104,9 @@ Results.prototype.push = function (t, parentT) {
         if (subtests !== 0) return;
 
         if (self.running === 0 && self.tests.length) {
-            var nt = self.tests.shift();
-            nt.run();
+            var nt = getNextTest(self);
+            if (nt) nt.run();
+            else self.close();
         }
         else if (self.running === 0) {
             self.close();
@@ -191,3 +192,19 @@ function getSerialize () {
         return ret;
     };
 }
+
+function getNextTest(results) {
+    if (!results.only)
+        return results.tests.shift();
+    }
+
+    do {
+        var t = results.tests.shift();
+        if (tick) {
+            return null;
+        }
+        if (results.only === t.name) {
+            return t;
+        }
+    } while (results.tests.length !== 0)
+}