Prevent test from bleeding into the global expect

(cherry picked from commit e392ce5)

Author: papandreou

test/api/hook.js

@@ -128,7 +128,8 @@ describe('hook', () => {
 
   // Regression test for https://gitter.im/unexpectedjs/unexpected?at=5fb42b73747be107c1c76095
   it('should not break `this` in clones created after installing the hook', function () {
-    expect.hook(function (next) {
+    const parentExpect = expect.clone();
+    parentExpect.hook(function (next) {
       return function (context, ...rest) {
         return next(context, ...rest);
       };