Backup task is not working on 8.15.pre
After gitlab-org/gitlab-ce!7188 , backup task is no longer working.
Deleting old backups ... rake aborted!
ArgumentError: comparison of Hash with Hash failed
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/manager.rb:91:in `sort'
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/manager.rb:91:in `block in remove_old'
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/manager.rb:84:in `chdir'
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/manager.rb:84:in `remove_old'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/backup.rake:22:in `block (3 levels) in <top (required)>'
/opt/gitlab/embedded/bin/bundle:22:in `load'
/opt/gitlab/embedded/bin/bundle:22:in `<main>'
This will also abort the upgrade because omnibus-gitlab package automatically triggers the backup task before upgrading.