fix branch name

Author: vomba

.github/workflows/build-image-builder.yml

@@ -7,19 +7,31 @@ on:
   pull_request:
 
 env:
-  TAG: ${{ github.ref_name }}
   IMAGE_NAME: image-builder
-  REGISTRY: ghcr.io/elastisys 
+  REGISTRY: ghcr.io/elastisys
 
 jobs:
   build-image-builder:
     runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v5
 
+      - name: Get branch name
+        id: get-branch-name
+        run: |
+          if [ "${{ github.event_name }}" == "pull_request" ]; then
+            echo "BRANCH_NAME=${{ github.head_ref }}" >> $GITHUB_OUTPUT
+          else
+            echo "BRANCH_NAME=${GITHUB_REF##*/}" >> $GITHUB_OUTPUT
+          fi
+        shell: bash
+
       - name: run make docker-build
         run: make docker-build
+        env:
+          TAG: ${{ steps.get-branch-name.outputs.BRANCH_NAME }}-${{ github.sha }}
 
       - name: run make docker-push
         run: make docker-push
-        
+        env:
+          TAG: ${{ steps.get-branch-name.outputs.BRANCH_NAME }}-${{ github.sha }}