title: PHPUnit is not producing its clover coverage report
body: <p>Although phpunit supports the <code>--coverage-clover [file]</code> argument, it seems to be doing nothing.</p>
  
  <p>I have Jenkins running on this server with the clover coverage plugin for php.</p>
  
  <p>Here's my output:</p>
  
  <pre><code>&gt; phpunit --coverage-clover coverage.xml
  ................................                                  32 / 32 (100%)
  
  Time: 745 ms, Memory: 16.75Mb
  
  &gt; ls -l
  (coverage.xml is not present)
  </code></pre>
  
  <p>I'm looking to find out why the clover XML file is not being generated at all, with no error message. Even using the <code>--debug</code> flag produces nothing related to the clover report.</p>
  
  <p>Version information:</p>
  
  <pre><code>&gt; phpunit --version
  PHPUnit 5.0.5 by Sebastian Bergmann and contributors.
  
  &gt; php --version
  PHP 5.6.14-1+deb.sury.org~trusty+1 (cli)
  Copyright (c) 1997-2015 The PHP Group
  Zend Engine v2.6.0, Copyright (c) 1998-2015 Zend Technologies
      with the ionCube PHP Loader + Intrusion Protection from ioncube24.com v.5.0.4, Copyright (c) 2002-2015, by ionCube Ltd.
      with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2015, by Zend Technologies
      with Xdebug v2.3.2, Copyright (c) 2002-2015, by Derick Rethans
  </code></pre>
  
  <p>This is my PHPUnit XML File:</p>
  
  <pre><code>&lt;phpunit bootstrap="tests/bootstrap.php"&gt;
      &lt;testsuites&gt;
          &lt;testsuite name="tests/suite"&gt;
              &lt;directory&gt;tests/suite&lt;/directory&gt;
          &lt;/testsuite&gt;
      &lt;/testsuites&gt;
  &lt;/‌​phpunit&gt;
  </code></pre>