try to parallelise git submodule fetch

Author: hjwp

.github/workflows/tests.yml

@@ -42,15 +42,20 @@ jobs:
             --mount type=volume,source=rootmount,target=/root \
             --mount type=bind,source=./,target=/app \
             -t hjwp/obeythetestinggoat-book-tester:latest \
-            git submodule foreach 'git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*" && git fetch origin'
-
-      # - name: check submodule branches
-      #   run: |
-      #     docker run --rm \
-      #       --mount type=volume,source=rootmount,target=/root \
-      #       --mount type=bind,source=./,target=/app \
-      #       -t hjwp/obeythetestinggoat-book-tester:latest \
-      #       bash -c "cd /app/source/chapter_01/superlists && git status && git branch -a"
+            git submodule foreach 'git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"'
+          docker run --rm \
+            --mount type=volume,source=rootmount,target=/root \
+            --mount type=bind,source=./,target=/app \
+            -t hjwp/obeythetestinggoat-book-tester:latest \
+            bash -c 'git submodule status | awk "{print $2}" | xargs -I% bash -c "cd % && git fetch"
+
+      - name: check submodule branches
+        run: |
+          docker run --rm \
+            --mount type=volume,source=rootmount,target=/root \
+            --mount type=bind,source=./,target=/app \
+            -t hjwp/obeythetestinggoat-book-tester:latest \
+            bash -c "cd /app/source/chapter_01/superlists && git status && git branch -a"
 
       - name: test chapter 1
         run: |