Adjust spec to build correct path when storage path ends in slash
CE backport of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5632. This isn't causing build failures in CE yet, but very well may in the future.
CE backport of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5632. This isn't causing build failures in CE yet, but very well may in the future.