title: Multiple sequential httpBackend requests cause unexpected request
body: <p>I'm testing a sequence that polls a resource until a condition is met.</p>
  
  <pre><code>Book = $resource("/books/:id", {id: "@id"});
  
  function poll(success) {
    Book.get({id:1}, function() {
      if (canStop) {
         success();
      } else {
         $timeout(poll, 1000);
      }
  
    });
  };
  </code></pre>
  
  <p>The test below fails with <code>Error: Unsatisfied requests: GET /user_workshops/1</code></p>
  
  <pre><code>describe('poll', function() {
    beforeEach(function() {
      $httpBackend.expectGET('/books/1').respond(200,{id:1});
      $httpBackend.expectGET('/books/1').respond(200,{id:1, newVal:1});
  
      poll(function() {
         successCalled = true;
      });
  
      $httpBackend.flush();
      $timeout.flush();
  
      canStop=true;
  
      $httpBackend.flush();
    });
  
    it('should call success when canStop is true', function() {
       expect(successCalled).toBe(true);
    });
  });
  </code></pre>
  
  <p>I've tried rearranging test order to put the second <code>expectGET</code> just before the second <code>httpBackend.flush()</code> but then I get:</p>
  
  <pre><code>Error: Unexpected request: POST /books/1
  No more request expected
  </code></pre>