gitlab:backup:create fails when 'backup_upload_remote_directory' doesn't exist

The Gitlab documentation says the following (my emphasis added):

The backup_upload_remote_directory must be set in addition to the local_root key. This is the sub directory inside the mounted directory that backups will be copied to, and will be created if it does not exist.

If you run gitlab:backup:create using the Local backup providing, and if the backup_upload_remote_directory does not exist, you get the following error:

root@gitlab:/etc/gitlab# gitlab-rake gitlab:backup:create --trace
<...SNIP...>
Creating backup archive: 1453758585_gitlab_backup.tar ... done
Uploading backup archive to remote storage gitlab ... rake aborted!
NoMethodError: undefined method `files' for nil:NilClass
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/manager.rb:47:in `upload'
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/manager.rb:30:in `block in pack'
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/manager.rb:13:in `chdir'
/opt/gitlab/embedded/service/gitlab-rails/lib/backup/manager.rb:13:in `pack'
/opt/gitlab/embedded/service/gitlab-rails/lib/tasks/gitlab/backup.rake:19:in `block (3 levels) in <top (required)>'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/task.rb:240:in `call'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/task.rb:240:in `block in execute'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/task.rb:235:in `each'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/task.rb:235:in `execute'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/task.rb:179:in `block in invoke_with_call_chain'
/opt/gitlab/embedded/lib/ruby/2.1.0/monitor.rb:211:in `mon_synchronize'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/task.rb:172:in `invoke_with_call_chain'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/task.rb:165:in `invoke'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/application.rb:150:in `invoke_task'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/application.rb:106:in `block (2 levels) in top_level'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/application.rb:106:in `each'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/application.rb:106:in `block in top_level'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/application.rb:115:in `run_with_threads'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/application.rb:100:in `top_level'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/application.rb:78:in `block in run'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/application.rb:176:in `standard_exception_handling'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/lib/rake/application.rb:75:in `run'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/gems/rake-10.4.2/bin/rake:33:in `<top (required)>'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/bin/rake:23:in `load'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/bin/rake:23:in `<main>'
Tasks: TOP => gitlab:backup:create

If the backup_upload_remote_directory does exist, the backup works as expected.

Found in 8.3.4