code: public function getTags()
      {
          if (null === $this->tags) {
              $tags = array();
  
              $this->process->execute('fossil tag list', $output, $this->checkoutDir);
              foreach ($this->process->splitLines($output) as $tag) {
                  $tags[$tag] = $tag;
              }
  
              $this->tags = $tags;
          }
  
          return $this->tags;
      }
docs: {@inheritDoc}