It's currently worked around in the lister but the surest fix would be that the manifest
corrects it itself.
There is already a 2,5 year old task [1] about this in the upstream repository. I've
pinged it (and also tried to have a look at it but i can't that fails... [2], i've
opened another issue about it)
[1] https://github.com/nix-community/nixpkgs-swh/issues/1
[2] https://github.com/nix-community/nixpkgs-swh/issues/5