[Robustness] use a null object cache

Author: ljharb

index.js

@@ -8,7 +8,7 @@
 'use strict';
 
 var url = require('url');
-var cache = {};
+var cache = { __proto__: null };
 
 function isChecksum(str) {
 	return (/^[a-f0-9]{40}$/i).test(str);

test/index.js

@@ -5,6 +5,8 @@ var test = require('tape');
 var gh = require('../');
 
 test('parse-github-url', function (t) {
+	t.equal(gh('toString').href, 'toString');
+
 	t.test('gets the user:', function (assert) {
 		assert.equal(gh(''), null);
 		assert.equal(gh('https://github.com/jonschlinkert/micromatch').owner, 'jonschlinkert');