fix branch existence checking

update-gluon.sh

@@ -27,7 +27,7 @@ git fetch upstream --tags
 git branch -a
 
 # we already have this branch - exit
-if ! git rev-parse --verify "$fork_newest_minor_branch" &> /dev/null; then
+if [ "$(git ls-remote --heads "$gluon_fork_git_url" "$fork_newest_minor_branch" | wc -l)" -gt 0 ]; then
     echo "Nothing todo, branch $fork_newest_minor_branch already exists"
     exit 0
 fi