Add unit test for kobo.hardlink.
Add unit test for kobo.hardlink.

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