Skipping an step in discourse rebuild

How can I skip the following step in discourse rebuild?

I how mounted a network filesystem in my upload folder, and chown-ing all files takes a lot of time in this situation.

cd /var/www/discourse && chown -R discourse:www-data /shared/log/rails /shared/uploads /shared/backups /shared/tmp

I can also do a umount before build and mount after build with app.yml, if its possible. But idk how to do it.