kdelfour/owncloud-docker — pull request #1 by paulocr (2014-11-08 14:29:31+00:00)
Title: Update Dockerfile

Original lines:
RUN chown -R www-data:www-data /var/www/owncloud
RUN mkdir /var/www/owncloud/data
RUN chmod -R 770 /var/www/owncloud/data

You create /var/www/owncloud/data after setting the chown therefore data is created without proper owner.