We were mixing up builds and steps. So for example
https://cache.nixos.org/log/2w66a98iqbjdppc5s2b8qvhi3gprvy45-freecell-solver-4.8.0.drv
at the moment contains the log for /nix/store/442r9d5ihbcpgq8q9dhijhvhlmplzp96-perl-namespace-autoclean-0.28.drv because the latter is a step in http://hydra.nixos.org/build/51300420. Oops.
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