this derivation will be built:
  /nix/store/9w6k45kh7ggdrmbzj7l2qnqi2lhnsl42-check-backlog-md.drv
9w6k45kh7ggdrmbzj7l2qnqi2lhnsl42-check-backlog-md.drv: bld4: not scheduled here: 9w6k45kh7ggdrmbzj7l2qnqi2lhnsl42-check-backlog-md.drv, asking the scheduler again