Revert "repos: remove NULL check on `gitserver_repos.clone_status`"
Created by: unknwon
Reverts sourcegraph/sourcegraph#24785 as per https://github.com/sourcegraph/sourcegraph/pull/24785#issuecomment-916038700.
Created by: unknwon
Reverts sourcegraph/sourcegraph#24785 as per https://github.com/sourcegraph/sourcegraph/pull/24785#issuecomment-916038700.