this derivation will be built:
  /nix/store/4x243hcv2x4ynzjc9f9mjs1mdyg4bhl9-harmonia-llvm-cov-3.3.0.drv
error: Cannot build '/nix/store/4x243hcv2x4ynzjc9f9mjs1mdyg4bhl9-harmonia-llvm-cov-3.3.0.drv'.
       Reason: builder failed with exit code 100.
       Output paths:
         /nix/store/b44nhmx409wz1f9zjpd6cc05xvx7hg55-harmonia-llvm-cov-3.3.0
       Last 25 log lines:
       >
       >     failures:
       >
       >     failures:
       >         test_build_log_endpoint
       >
       >     test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.75s
       >
       >   stderr ───
       >     Error: "No available ports"
       >
       > ────────────
       >      Summary [   0.776s] 10/2457 tests run: 0 passed, 10 failed, 0 skipped
       >         FAIL [   0.026s] (   1/2457) harmonia-cache::endpoints test_root_endpoint
       >         FAIL [   0.033s] (   2/2457) harmonia-cache::security_paths malformed_hash_is_4xx_not_5xx
       >         FAIL [   0.033s] (   3/2457) harmonia-cache::endpoints test_root_endpoint_with_signing_keys
       >         FAIL [   0.033s] (   4/2457) harmonia-cache::prometheus test_prometheus_metrics
       >         FAIL [   0.033s] (   5/2457) harmonia-cache::endpoints test_health_endpoint
       >         FAIL [   0.033s] (   6/2457) harmonia-cache::realisations test_build_trace_endpoint
       >         FAIL [   0.334s] (   7/2457) harmonia-cache::error_responses serve_missing_file_does_not_leak_fs_path
       >         FAIL [   0.335s] (   8/2457) harmonia-cache::retry test_download_retry_over_flaky_connection
       >         FAIL [   0.412s] (   9/2457) harmonia-cache::chroot test_chroot
       >         FAIL [   0.775s] (  10/2457) harmonia-cache::log test_build_log_endpoint
       > warning: 2447/2457 tests were not run due to test failure (run with --no-fail-fast to run all tests, or run with --max-fail)
       > error: test run failed
       For full logs, run:
         nix log /nix/store/4x243hcv2x4ynzjc9f9mjs1mdyg4bhl9-harmonia-llvm-cov-3.3.0.drv