#369 Only pull Container image if necessary

The container image usually should be there due to previous build step

Author: ascheman

.github/workflows/gradle-build.yml

@@ -33,9 +33,10 @@ jobs:
 
       - name: Prepare Docker image for test
         run: |
-          tag=$(git branch --show-current | tr '/' '-')
-          docker pull ghcr.io/aim42/hsc:${tag}
-          docker tag ghcr.io/aim42/hsc:${tag} ghcr.io/aim42/hsc:v2
+          tag="${GITHUB_REF_NAME:=$(git branch --show-current)}"
+          tag="${tag/\//-}"
+          (docker images | egrep -q "ghcr.io/aim42/hsc\\s+${tag}\\s+") || docker pull "ghcr.io/aim42/hsc:${tag}"
+          docker tag "ghcr.io/aim42/hsc:${tag}" ghcr.io/aim42/hsc:v2
 
       - name: Download Artifacts
         uses: actions/download-artifact@v5