fixup! fix(build): use per-worker slot store

buildbot_nix/__init__.py

@@ -622,6 +622,20 @@ def nix_build_config(
 ) -> util.BuilderConfig:
     """Builds one nix flake attribute."""
     factory = util.BuildFactory()
+    factory.addStep(
+        steps.ShellCommand(
+            name="Copy the derivation to the local worker store",
+            command=[
+                "nix",
+                "copy",
+                "--to",
+                "../store",
+                "--no-check-sigs",
+                util.Interpolate("%(prop:drv_path)s^*")
+            ]
+        )
+    )
+
     factory.addStep(
         NixBuildCommand(
             env={},