Add a warning about a possibly read-only database to the worker middleware assert.
Add a warning about a possibly read-only database to the worker middleware assert.

release-engineering/kobo,pombredanne/https-git.fedorahosted.org-git-kobo,pombredanne/https-git.fedorahosted.org-git-kobo,release-engineering/kobo,pombredanne/https-git.fedorahosted.org-git-kobo,release-engineering/kobo,release-engineering/kobo,pombredanne/https-git.fedorahosted.org-git-kobo