title: Fabric: Answers: purchase flow tracking of `success` bool doesn't work as expected
body: <p>I'm tracking purchase-related events in an iOS app with Answers (part of Fabric). The Answers docs for <a href="https://docs.fabric.io/apple/answers/answers-events.html#purchase" rel="nofollow noreferrer">purchase flow tracking</a> are very straightforward:</p>
  
  <pre><code>Answers.logPurchaseWithPrice(13.50,
                    currency: "USD",
                    success: true,
                    itemName: "Answers Shirt",
                    itemType: "Apparel",
                    itemId: "sku-350",
                    customAttributes: nil)
  </code></pre>
  
  <p>The <code>success</code> bool is documented as:</p>
  
  <blockquote>
    <p>When a Purchase Event has the success attribute set to NO (Objective-C) or false (Swift), it is excluded from revenue charts but included in all other charts and calculations.</p>
  </blockquote>
  
  <p>I've submitted one full flow of events, through Add Cart, Start Checkout, and Purchase, and for Purchase (<code>logPurchase…</code>) I set <code>success</code> to <code>false</code>, because I took the cancellation route, rather than completing the payment.</p>
  
  <p>However, when I look at Answers' Purchase Funnel, I see a 100% purchase success rate:</p>
  
  <p><a href="https://i.stack.imgur.com/yx8hx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yx8hx.png" alt="enter image description here"></a></p>
  
  <p>That's not quite right! What's the proper Answers tracking call for a user tapping Cancel in my Purchase flow? It doesn't seem to be <code>logPurchaseWithPrice(… success: false…</code></p>