It works by checking if your branchs' gerrit change id is present in master
if yes it adds the branch to the list of branches to clean.
You must run it with --confirm to delete otherwise only a dry-run will be done
You can also run it with --one-by-one where it will ask you to confirm each branch deletion
Change-Id: Iaabe1a6db72242fd31b14302fb3109e8545a0ad8
