.gitlab-ci.yml "only" REGEX does not work

In the Gitlab CI YML documentation it states that you may specify a REGEX for the "only" keyword: http://doc.gitlab.com/ci/yaml/README.html

Based on this documentation I would expect that if my REGEX is set to "/^sandbox-.*$/" then a tag that was pushed to origin with the name of "sandbox-2015-11-20-1441" would trigger a build.

It does not.

However, if I do NOT us a REGEX it works.

The REGEX feature appears to be broken...