Set default branch from manifest on restore
Now that we write manifest files for all backups we can use it to store HEAD of the repository being backed up. This allows HEAD to be set precisely, even when there's no bundle file.
Once merged, this will work immediately for server-side but regular backups need to have backup.rake send the restore ID (rather than latest) so that the manifest file will be picked up (https://gitlab.com/gitlab-org/gitlab/-/blob/d2827dbc7dabbe84b94d467104a98c082fb2e79c/lib/backup/gitaly_backup.rb#L95)
Edited by James Fargher