title: Runtime exception with Composer install/update on shared hosting w/ Symfony2
body: <p>I seem to be having some problems with cache permissions on shared hosting.  Specifically, when I try to install/update vendors via Composer, I get a runtime exception:</p>
  
  <pre><code>$ php composer.phar update -v -o
  
  Script Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::clearCache handling the post-update-cmd event terminated with an exception
  
  [RuntimeException]
  An error occurred when executing the "'cache:clear --no-warmup'" command.
  
  Exception trace:
  () at /home/thesewingdiva/private/vendor/sensio/distribution-bundle/Sensio/Bundle/DistributionBundle/Composer/ScriptHandler.php:137
  Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::executeCommand() at /home/thesewingdiva/private/vendor/sensio/distribution-bundle/Sensio/Bundle/DistributionBundle/Composer/ScriptHandler.php:48
  Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::clearCache() at phar:///home/thesewingdiva/private/composer.phar/src/Composer/Script/EventDispatcher.php:122
  Composer\Script\EventDispatcher-&gt;executeEventPhpScript() at phar:///home/thesewingdiva/private/composer.phar/src/Composer/Script/EventDispatcher.php:101
  Composer\Script\EventDispatcher-&gt;doDispatch() at phar:///home/thesewingdiva/private/composer.phar/src/Composer/Script/EventDispatcher.php:74
  Composer\Script\EventDispatcher-&gt;dispatchCommandEvent() at phar:///home/thesewingdiva/private/composer.phar/src/Composer/Installer.php:237
  Composer\Installer-&gt;run() at phar:///home/thesewingdiva/private/composer.phar/src/Composer/Command/UpdateCommand.php:82
  Composer\Command\UpdateCommand-&gt;execute() at phar:///home/thesewingdiva/private/composer.phar/vendor/symfony/console/Symfony/Component/Console/Command/Command.php:238
  Symfony\Component\Console\Command\Command-&gt;run() at phar:///home/thesewingdiva/private/composer.phar/vendor/symfony/console/Symfony/Component/Console/Application.php:193
  Symfony\Component\Console\Application-&gt;doRun() at phar:///home/thesewingdiva/private/composer.phar/src/Composer/Console/Application.php:101
  Composer\Console\Application-&gt;doRun() at phar:///home/thesewingdiva/private/composer.phar/vendor/symfony/console/Symfony/Component/Console/Application.php:106
  Symfony\Component\Console\Application-&gt;run() at phar:///home/thesewingdiva/private/composer.phar/src/Composer/Console/Application.php:74
  Composer\Console\Application-&gt;run() at phar:///home/thesewingdiva/private/composer.phar/bin/composer:37
  require() at /home/thesewingdiva/private/composer.phar:15
  
  update [--prefer-source] [--prefer-dist] [--dry-run] [--dev] [--no-custom-installers] [--no-scripts] [--no-progress] [-v|--verbose] [-o|--optimize-autoloader] [packages1] ... [packagesN]
  </code></pre>
  
  <p>I don't have the ability to use ACL, and I don't have the ability to use sudo since it's shared hosting.  The cache is set to 777 for it's permissions (recursive), and app/console, app.php, and app_dev.php all have umask(0000).  I've also erased the cache to see if that would help.  No dice.  Any ideas on how to fix this?</p>