git-merge-customizations: Fix a hard-coded remote configuration

Author: sschuberth

git/git-merge-customizations

@@ -14,5 +14,9 @@ fi
 echo "Resetting branch to '$UPSTREAM_BRANCH'..."
 git reset --hard $UPSTREAM_BRANCH
 
-echo "Merging '$CUSTOMIZATION_BRANCHES' into '$CURRENT_BRANCH'..."
-git for-each-ref --format='%(refname)' refs/remotes/internal/ort-pipeline-customizations | xargs -n1 git merge --no-ff
+echo "Merging the following branches into '$CURRENT_BRANCH'..."
+for BRANCH in $CUSTOMIZATION_BRANCHES; do
+    echo $BRANCH
+done
+
+git merge --no-ff $CUSTOMIZATION_BRANCHES