In the previous attempt to add this feature, I had forgotten to add the
new tests to tests/default.nix, which meant I believed the feature
worked when it did not. Additionally, real world testing shows that if
the path does not exist on the remote already, that nix build --store
will not work and will throw the following error: 'path '/nix/store/foo'
is required, but there is no substituter that can build it' To fix this,
I've decided to use nix copy --derivation and then nix-store --realise
on the remote. A lot of refactoring is needed to make this codebase
presentable anyway, so this hack is fine for now, though it is
admittedly an unclean implementation.
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