Merge pull request #465 from NixOS/ci

tests/run: enable experimental nix-command

CONTRIBUTING.md

@@ -45,5 +45,11 @@ Link the profile in the table in README.md and in flake.nix.
 Run ./tests/run.py to test building. The test script script will parse all the
 profiles from the README.md.
 
+You can also just specify a single profile like this:
+
+```
+ ./tests/run.py '<nixos-hardware/purism/librem/15v3>'
+```
+
 Because profiles can only be tested with the appropriate hardware, quality
 assurance is up to *you*.

tests/run.py

@@ -38,6 +38,7 @@ def build_profile(
     cmd = [
         "nix",
         "build",
+        "--extra-experimental-features", "nix-command",
         "-f",
         "build-profile.nix",
         "-I",