Provides a small (~7.5%) reduction in the test runtime measured for the external
test:
Before:
```
Benchmark 1: nix build .#hydraJobs.x86_64-linux.external-unstable --rebuild
Time (mean ± σ): 151.737 s ± 1.074 s [User: 0.310 s, System: 0.289 s]
Range (min … max): 150.321 s … 153.512 s 10 runs
```
After:
```
Benchmark 1: nix build .#hydraJobs.x86_64-linux.external-unstable --rebuild
Time (mean ± σ): 140.647 s ± 1.092 s [User: 0.331 s, System: 0.296 s]
Range (min … max): 138.536 s … 142.298 s 10 runs
```