add only if branch is not set

hack/build-image.sh

@@ -40,8 +40,8 @@ fi
 repository=ghcr.io/kcp-dev/kcp
 architectures="amd64 arm64"
 
-# when building locally, just tag with the current HEAD hash with a "dev-" prefix for GC.
-version="dev-$(git rev-parse --short HEAD)"
+# when building locally, just tag with the current HEAD hash.
+version="$(git rev-parse --short HEAD)"
 branchName=""
 
 # deduce the tag from the Prow job metadata
@@ -60,6 +60,11 @@ if [ -n "${PULL_BASE_REF:-}" ]; then
   fi
 fi
 
+# Prefix with "dev-" if not on a tag or branch
+if [ -z "$branchName" ]; then
+  version="dev-$version"
+fi
+
 image="$repository:$version"
 echo "Building container image $image ..."