nixpkgs/nixos/modules/services/continuous-integration
Bas van Dijk ad554b3e4e hydra: only set buildMachinesFiles when nix.buildMachines is defined
This applies [hydra PR #432](https://github.com/NixOS/hydra/pull/432)
to the NixOS module in nixpkgs:

```
commit 4efd078977e5ea20e1104783efc324cba11690bc
Author: Bas van Dijk <v.dijk.bas@gmail.com>
Date:   Sun Dec 11 15:35:38 2016 +0100

    Only set buildMachinesFiles when nix.buildMachines is defined
```
2020-01-14 12:32:40 +01:00
..
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2017-08-23 18:23:13 +00:00