The pipeline editor does not work on branches

https://sentry.gitlab.net/gitlab/gitlabcom/issues/2660056/?referrer=gitlab_plugin

GRPC::InvalidArgument: 3:TreeEntry: empty revision.
  grpc-1.30.2-x86_64 (linux) src/ruby/lib/grpc/generic/active_call.rb:29:in `check_status'
  grpc-1.30.2-x86_64 (linux) src/ruby/lib/grpc/generic/active_call.rb:180:in `attach_status_results_and_complete_call'
  grpc-1.30.2-x86_64 (linux) src/ruby/lib/grpc/generic/active_call.rb:169:in `receive_and_check_status'
  grpc-1.30.2-x86_64 (linux) src/ruby/lib/grpc/generic/active_call.rb:337:in `each_remote_read_then_finish'