actions: shell: assert sh fallback (#790)

Refs forgejo/runner#150

Local testing [following instructions](https://code.forgejo.org/forgejo/end-to-end/src/branch/main/README.md#running-from-locally-built-binary) and [the matching ACT PR](https://code.forgejo.org/forgejo/act/pulls/177).

Once merged this will be a noop and actually remove coverage for shell test that was added earlier today. It will reactivate once the runner v8.0.0 is published.

Reviewed-on: https://code.forgejo.org/forgejo/end-to-end/pulls/790
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

actions/example-shell/.forgejo/workflows/test.yml

@@ -12,10 +12,29 @@ jobs:
         run: |
             ${{ env.ASSERT_SHELL }} /bash
 
-  defaults-run:
+  sh-fallback:
     needs: [default]
     # alpine:docker://code.forgejo.org/oci/alpine:latest
     runs-on: alpine
+    steps:
+      - name: default is bash but with a fallback to sh in case it does not exist
+        run: |
+            ${{ env.ASSERT_SHELL }} /busybox
+
+  sh-fallback-with-container:
+    needs: [sh-fallback]
+    runs-on: docker
+    container:
+      image: code.forgejo.org/oci/alpine:latest
+    steps:
+      - name: default is bash but with a fallback to sh in case it does not exist
+        run: |
+            ${{ env.ASSERT_SHELL }} /busybox
+
+  defaults-run:
+    needs: [sh-fallback-with-container]
+    # alpine:docker://code.forgejo.org/oci/alpine:latest
+    runs-on: alpine
     defaults:
         run:
             shell: sh
@@ -24,16 +43,6 @@ jobs:
         run: |
             ${{ env.ASSERT_SHELL }} /busybox
 
-  alpine:
-    needs: [defaults-run]
-    runs-on: docker
-    container:
-      image: code.forgejo.org/oci/alpine:latest
-    steps:
-      - name: default is sh which is an alias for busybox in alpine
-        run: |
-            ${{ env.ASSERT_SHELL }} /busybox
-
   python:
     needs: [alpine]
     runs-on: docker
@@ -51,9 +60,9 @@ jobs:
     container:
       image: code.forgejo.org/oci/node:22-bookworm
     steps:
-      - name: default is sh which is an alias for dash in bookworm
+      - name: default is bash
         run: |
-            ${{ env.ASSERT_SHELL }} /dash
+            ${{ env.ASSERT_SHELL }} /bash
 
       - name: bash => bash --noprofile --norc -e -o pipefail {0}
         shell: bash