buildsys: use per-package output directory (fixup)

Author: webern

tools/buildsys/src/builder.rs

@@ -303,12 +303,7 @@ impl DockerBuild {
         image_features: HashSet<ImageFeature>,
     ) -> Result<Self> {
         let package = manifest.info().package_name();
-        let per_package_dir = format!(
-            "{}/{}",
-            args.packages_dir.display(),
-            manifest.info().manifest_name()
-        )
-        .into();
+        let per_package_dir = format!("{}/{}", args.packages_dir.display(), package).into();
 
         Ok(Self {
             dockerfile: args.common.tools_dir.join("build.Dockerfile"),