nixpkgs-update: shellcheck, shfmt worker script

hosts/build02/worker.bash

@@ -28,7 +28,7 @@ while true; do
     sleep 60
     ;;
   JOB\ *)
-      read -r attr_path payload <<< "${response#JOB }"
+    read -r attr_path payload <<<"${response#JOB }"
     # If one worker is initializing the nixpkgs clone, the other will
     # try to use the incomplete clone, consuming a bunch of jobs and
     # throwing them away. So we use a crude locking mechanism to
@@ -47,5 +47,6 @@ while true; do
       sleep 10
     done
     run-nixpkgs-update
+    ;;
   esac
 done