title: Gerrit hooks redirection
body: <p>Are you using any hooks for gerrit? I need one to scan the patchset.</p>
  
  <p>I tried to create update hooks under <code>GIT_DIR/hooks/</code>, but gerrit will bypass that hook when merge, while it works when pushing to git directly.
  Then I tried to create <code>gerrit_site/hooks/patchset_created</code> with <strong>+x</strong> permission. I can see the error_log like '<code>echo $GIT_DIR</code>', but the message cannot redirect to user interface like ssh terminal. Also exit 0 and 1 doesn't block the pushing.</p>
  
  <p>Is it possible for the gerrit hook acts as git one which can redirect message to user and block some patchset? </p>