Invalidate old external cache archives

.gitea/workflows/build.yml

@@ -51,7 +51,7 @@ jobs:
         run: |
           git submodule status --cached --recursive > .ci-submodules.lock
           DEPENDS_KEY="$(cat contrib/depends/Makefile contrib/depends/funcs.mk contrib/depends/hosts/*.mk contrib/depends/packages/*.mk contrib/depends/toolchain.cmake.in | sha256sum | cut -d' ' -f1)"
-          echo "EXTERNAL_CACHE_KEY=$(sha256sum .ci-submodules.lock | cut -d' ' -f1)" >> "$GITHUB_ENV"
+          echo "EXTERNAL_CACHE_KEY=v2-$(sha256sum .ci-submodules.lock | cut -d' ' -f1)" >> "$GITHUB_ENV"
           echo "DEPENDS_CACHE_KEY=${DEPENDS_KEY}" >> "$GITHUB_ENV"
 
       - name: Restore external cache
@@ -63,7 +63,13 @@ jobs:
             rm -rf external .git/modules/external
             mkdir -p external .git/modules
             tar --zstd -xf "${EXTERNAL_ARCHIVE}"
-            echo "EXTERNAL_CACHE_HIT=true" >> "$GITHUB_ENV"
+            if [ -d ".git/modules/external" ]; then
+              echo "EXTERNAL_CACHE_HIT=true" >> "$GITHUB_ENV"
+            else
+              echo "External cache is missing .git/modules/external, ignoring it"
+              rm -rf external .git/modules/external
+              echo "EXTERNAL_CACHE_HIT=false" >> "$GITHUB_ENV"
+            fi
           else
             echo "No external cache found"
             echo "EXTERNAL_CACHE_HIT=false" >> "$GITHUB_ENV"