What's going on?

error.txt

copying path '/nix/store/cq155md2522yhjyzyxvxpy8rds1wiva3-source' from 'https://cache.nixos.org'...
these derivations will be built:
  /nix/store/alzxdc6ns0bxrglwbl0841x11pvm1i0v-docker-image-sitespeedio-sitespeed.io-latest.tar.drv
  /nix/store/n24rwcn6x5sikddb0pvfhx2bfs8ximns-docker-layer-sitesped-runner.drv
  /nix/store/zd8wp7xq0zqy0pnfblmv21zy5xj2p2bb-runtime-deps.drv
  /nix/store/iy0d8v2cxw0q4v84kw25dzig6fwcfh5p-docker-image-sitesped-runner.tar.gz.drv
building '/nix/store/alzxdc6ns0bxrglwbl0841x11pvm1i0v-docker-image-sitespeedio-sitespeed.io-latest.tar.drv'...
building '/nix/store/n24rwcn6x5sikddb0pvfhx2bfs8ximns-docker-layer-sitesped-runner.drv'...
time="2018-12-10T12:07:58Z" level=fatal msg="Invalid source name docker://sitespeedio/sitespeed.io@sh256:8ad85e4556ab214e4a5a38dfc8f84e9b3da07114c2414700eb9b8a69092f7071: unsupported digest algorithm"
builder for '/nix/store/alzxdc6ns0bxrglwbl0841x11pvm1i0v-docker-image-sitespeedio-sitespeed.io-latest.tar.drv' failed with exit code 1                                               
cannot build derivation '/nix/store/iy0d8v2cxw0q4v84kw25dzig6fwcfh5p-docker-image-sitesped-runner.tar.gz.drv': 1 dependencies couldn't be built                                      
error: build of '/nix/store/iy0d8v2cxw0q4v84kw25dzig6fwcfh5p-docker-image-sitesped-runner.tar.gz.drv' failed

pullImage.nix

{
  siteSpeedImage = dockerTools.pullImage {
    imageName = "sitespeedio/sitespeed.io";
    imageDigest = "sh256:8ad85e4556ab214e4a5a38dfc8f84e9b3da07114c2414700eb9b8a69092f7071";
    sha256 = "0l2iw2frphfddvm6x9pgy08h2wn50jiy9jl639z6a1r9mamqf6hv";
  };
}