error: selector 'ghc-8.6.5' matches no derivations

When I try to build locally, I get the following error.

```
[...]
copying path '/nix/store/zr2xa2p96vl77s0ykazkiwiy48qsvqv8-libssh2-1.9.0' from 'https://cache.nixos.org'...
copying path '/nix/store/kjfmrxyxcah0m1z7m363razpqa0js839-sqlite-3.31.0' from 'https://cache.nixos.org'...
copying path '/nix/store/a9s0054mxq988hivxdnqmzq7349fkblx-curl-7.68.0' from 'https://cache.nixos.org'...
copying path '/nix/store/s0a0z1vnr8jl6vg5wji560pjvhh9pjy8-aws-sdk-cpp-1.7.90' from 'https://cache.nixos.org'...
copying path '/nix/store/r339ch78qzxlq20y1i09b19njxzjk5mr-nix-2.3.3' from 'https://cache.nixos.org'...
copying path '/nix/store/js4gg8mq3af9dvhanwn80rgfz82sqpp0-cachix-0.3.7' from 'https://cache.nixos.org'...
building '/nix/store/2cxrwb9qw52g18xm1fzpq8z7ysrln65a-user-environment.drv'...
created 25 symlinks in user environment
Configured https://all-hies.cachix.org binary cache in /etc/nix/nix.conf
error: selector 'ghc-8.6.5' matches no derivations
The command '/bin/sh -c nix-env -iA cachix -f https://cachix.org/api/v1/install && cachix use all-hies && nix-env -i ghc-8.6.5 && nix-env -iA unstableFallback.selection --arg selector 'p: { inherit (p) ghc865; }' -f https://github.com/infinisil/all-hies/tarball/master' returned a non-zero code: 1
```

Start by reproducing the Docker build and inspect the failing nix-env command, especially the ghc-8.6.5 selector and the all-hies fallback selection. Done means the image build completes without the selector error and installs the intended GHC and HIE versions.

Written by the indexing model from the issue text.