deleting a branch

> "rm -f .git/refs/heads/no-longer-needed".  Make sure your
> working tree is not on that branch (i.e. .git/HEAD should not be
> pointing at it).
> 
> I have not introduced "git branch -d no-longer-needed" because
> I think that should do a bit more than "rm -f".  For example:
> 
>  - making sure you are not on that branch (obvious),
> 
>  - check if all changes on that branch are included in the
>    master branch or some other branch (easy if we hardcode "master";
>    checking all other branches might be nicer but expensive).

> The new flag '-d' lets you delete a branch.  For safety, it does not
> lets you delete the branch you are currently on, nor a branch that
> has been fully merged into your current branch.
> 
> The credit for the safety check idea goes to Daniel Barkalow.
> 
> Signed-off-by: Junio C Hamano <junkio@cox.net>
> 
> ---
> 
>  git-branch.sh |   60 +++++++++++++++++++++++++++++++++++++++++++++++++++------
>  1 files changed, 54 insertions(+), 6 deletions(-)
> 
> 6a714989f83ccb93188dc37791da8a0f2e32cabe
> diff --git a/git-branch.sh b/git-branch.sh
> --- a/git-branch.sh
> +++ b/git-branch.sh
> @@ -3,7 +3,7 @@
>  . git-sh-setup || die "Not a git archive"
>  
>  usage () {
> -    echo >&2 "usage: $(basename $0)"' [<branchname> [start-point]]
> +    echo >&2 "usage: $(basename $0)"' [-d <branch>] | [<branch> [start-point]]
>  
>  If no arguments, show available branches and mark current branch with a star.
>  If one argument, create a new branch <branchname> based off of current HEAD.
> @@ -12,6 +12,59 @@ If two arguments, create a new branch <b
>      exit 1
>  }
>  
> +delete_branch () {
> +    option="$1" branch_name="$2"
> +    headref=$(readlink "$GIT_DIR/HEAD" | sed -e 's|^refs/heads/||')
> +    case ",$headref," in
> +    ",$branch_name,")
> +	die "Cannot delete the branch you are on." ;;
> +    ,,)
> +	die "What branch are you on anyway?" ;;
> +    esac
> +    branch=$(cat "$GIT_DIR/refs/heads/$branch_name") &&
> +	branch=$(git-rev-parse --verify "$branch^0") ||
> +	    die "Seriously, what branch are you talking about?"
> +    case "$option" in
> +    -D)
> +	;;
> +    *)
> +	mbs=$(git-merge-base -a "$branch" HEAD | tr '\012' ' ')
> +	case " $mbs " in
> +	*' '$branch' '*)
> +	    # the merge base of branch and HEAD contains branch --
> +	    # which means that the HEAD contains everything in the HEAD.
> +	    ;;
> +	*)
> +	    echo >&2 "The branch '$branch_name' is not a strict subset of your current HEAD.
> +If you are sure you want to delete it, run 'git branch -D $branch_name'."
> +	    exit 1
> +	    ;;
> +	esac
> +	;;
> +    esac
> +    rm -f "$GIT_DIR/refs/heads/$branch_name"
> +    echo "Deleted branch $branch_name."
> +    exit 0
> +}
> +
> +while case "$#,$1" in 0,*) break ;; *,-*) ;; *) break ;; esac
> +do
> +	case "$1" in
> +	-d | -D)
> +		delete_branch "$1" "$2"
> +		exit
> +		;;
> +	--)
> +		shift
> +		break
> +		;;
> +	-*)
> +		usage
> +		;;
> +	esac
> +	shift
> +done
> +
>  case "$#" in
>  0)
>  	headref=$(readlink "$GIT_DIR/HEAD" | sed -e 's|^refs/heads/||')
> @@ -36,11 +89,6 @@ case "$#" in
>  esac
>  branchname="$1"
>  
> -case "$branchname" in
> --*)
> -	usage;;
> -esac
> -
>  rev=$(git-rev-parse --verify "$head") || exit
>  
>  [ -e "$GIT_DIR/refs/heads/$branchname" ] && die "$branchname already exists"
>