The `-redirect-http` flag doesn't support non-default ports

Discovered in https://gitlab.com/gitlab-org/gitlab-pages/merge_requests/21/diffs#note_25242507 - redirects will come back with the HTTPS scheme, but the HTTP port.

This use case seems to be generally broken: https://gitlab.com/gitlab-org/gitlab-pages/issues/51

mentioned in issue #51 (closed)

mentioned in merge request !21 (merged)

mentioned in issue #56 (closed)

mentioned in merge request !28 (closed)