title: `CakeResponse` referencing undefined variables in `compact()` call triggers errors/notices
body: <p>I’m updating my first CakePHP application on a web server, but pages show errors which are at the end of this post. I can’t find the file(s) which have not uploded correctly. Thanks for help.</p>
  <p>CakePHP version : <strong>2.9</strong></p>
  <p>Error messages :</p>
  <blockquote>
  <p>Notice (8): compact(): Undefined variable: etagMatches [CORE/Cake/Network/CakeResponse.php, line 1171]*</p>
  </blockquote>
  <blockquote>
  <p>Notice (8): compact() [function.compact]: Undefined variable: timeMatches [CORE/Cake/Network/CakeResponse.php, line 1171]*</p>
  </blockquote>
  <blockquote>
  <p>Notice (8): compact() [function.compact]: Undefined variable: subject [CORE/Cake/Utility/ObjectCollection.php, line 128]*</p>
  </blockquote>