title: Mockery fails with 'Could not load mock ... class already exists' when running with --code-coverage
body: <p>I am trying to mock a class for phpunit. Php unit fails with the error <code>Could not load mock ... class already exists</code>. This is the only test I'm running, so it can't be the case that the class is mocked already.</p>
  
  <p>Any suggestion would be appreciated.</p>
  
  <p>Here is the error case:
      
  
  <pre><code>namespace Tests\Feature;
  
  use Tests\TestCase;
  
  class DeactivateACSTest extends TestCase
  {
      public function testDeactivateAcs()
      {
          $deviceController = \Mockery::mock('overload:App\Http\Controllers\Cloud\DeviceController');
          $deviceController
              -&gt;shouldReceive('deactivateACS')
              -&gt;andReturn('hilfehilfehilfe');
  
          $devCon = new \App\Http\Controllers\Cloud\DeviceController();
          $this-&gt;assertEquals('hilfehilfehilfe', $devCon-&gt;deactivateACS());
      }
  }
  </code></pre>
  
  <p>When running it without <code>--code-coverage</code> it works:</p>
  
  <pre><code>[13:10:15] vagrant@homestead [~/Code/ekp] $ phpunit --filter DeactivateACS
  PHPUnit 6.5.10 by Sebastian Bergmann and contributors.
  
  
   ==&gt; Tests\Feature\DeactivateACSTest              ✓
  
  Time: 1.08 seconds, Memory: 16.00MB
  
  OK (1 test, 3 assertions)
  </code></pre>
  
  <p>However, when running it with <code>--code-coverage</code> it fails:</p>
  
  <pre><code>[13:10:23] vagrant@homestead [~/Code/ekp] $ phpunit --coverage-html coverage --coverage-text=code_coverage.txt --filter DeactivateACSTest
  PHPUnit 6.5.10 by Sebastian Bergmann and contributors.
  
  
    ==&gt; Tests\Feature\DeactivateACSTest              ⚈
  
  Time: 5.79 seconds, Memory: 44.00MB
  
  There was 1 error:
  
  1) Tests\Feature\DeactivateACSTest::testDeactivateAcs
  Mockery\Exception\RuntimeException: Could not load mock \App\Http\Controllers\Cloud\DeviceController, class already exists
  
  /home/vagrant/Code/ekp/vendor/mockery/mockery/library/Mockery/Container.php:220
  /home/vagrant/Code/ekp/vendor/mockery/mockery/library/Mockery.php:116
  /home/vagrant/Code/ekp/tests/Feature/DeactivateACSTest.php:11
  
  ERRORS!
  Tests: 1, Assertions: 0, Errors: 1.
  
  Generating code coverage report in HTML format ... done
  </code></pre>