title: Cookie set to expire on session end cannot be prematurely 'deleted'
body: <p>I've been testing cookie creation, amendment, and deletion, and have come across a "quirk" that I cannot seem to explain.</p>
  
  <p>I can create a cookie with a 30-day expiry as normal:</p>
  
  <pre><code>setcookie("test_cookie", "test_value", time() + (86400 * 30), "/");
  </code></pre>
  
  <p>And I can then "delete" that cookie with ease:</p>
  
  <pre><code>setcookie("test_cookie", "", time() - 3600, "/");
  </code></pre>
  
  <p>However, the quirk comes when I create a cookie with an expiry time of <code>0</code> (i.e. will expire on browser close/session end):</p>
  
  <pre><code>setcookie("test_cookie", "test_value", 0, "/");
  </code></pre>
  
  <p>I am now unable to remove that cookie manually, without closing the browser! Setting it's expiry to a time in the past does nothing. What gives?</p>
  
  <p>The whole page I've been using for testing, commenting out lines I'm not using:</p>
  
  <pre><code>&lt;!doctype html&gt;
  &lt;html lang="en"&gt;
  &lt;head&gt;
      &lt;meta charset="utf-8"&gt;
      &lt;title&gt;Cookie Test&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;?php
      // setcookie("test_cookie", "test_value", time() + (86400 * 30), "/");
      // setcookie("test_cookie", "test_value_updated", time() + (86400 * 30), "/");
      // setcookie("test_cookie", "", time() - 3600, "/");
  
      // setcookie("test_cookie", "test_value", 0, "/");
      // setcookie("test_cookie", "test_value_updated", 0, "/");
      setcookie("test_cookie", "", time() - 3600, "/");
      print_r($_COOKIE);
      ?&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>