die "invalid branch name: $name"
baserev="$(git rev-parse --verify "refs/top-bases/$name" 2>/dev/null)" ||
die "not a TopGit topic branch: $name"
-! git symbolic-ref HEAD || [ "$(git symbolic-ref HEAD)" != "refs/heads/$name" ] ||
+! git symbolic-ref HEAD >/dev/null || [ "$(git symbolic-ref HEAD)" != "refs/heads/$name" ] ||
die "cannot delete your current branch"
nonempty=