Customer in https://gitlab.com/gitlab-org/gitlab-ee/issues/3229 was using Redmine, but the GitLab issue tracker was still active. As a result, I think (but have not verified) the existing Markdown stored in the DB may have not been rendered properly, and so links to the external issue tracker are not rendered until someone edits the text. We do have a `cached_markdown_version` field, but this is mostly an internal version number. /cc: @victorwu, @smcgivern