git-stack

#!/bin/bash
# git-stack: create a new branch stacked on the current one
set -e

# Work around kcov --bash-handle-sh-invocation (v42) duplicating argv[0] into $1.
# See kcov src/engines/bash-execve-redirector.c — its argv-rebuild loop starts
# at i=0, so the script path arrives twice. Shift it off if we see it.
if [ $# -gt 0 ] && { [ "$1" = "$0" ] || [ "$1" = "${0##*/}" ]; }; then
    shift
fi

if [ -z "$1" ]; then
    echo "Usage: git stack <branch-name>"
    exit 1
fi

CURRENT=$(git branch --show-current)
if [ -z "$CURRENT" ]; then
    echo "Error: not on a branch."
    exit 1
fi

NEW="$1"

if git show-ref --verify --quiet "refs/heads/$NEW"; then
    echo "Error: branch '$NEW' already exists."
    exit 1
fi

git checkout -b "$NEW"
git config "branch.$NEW.stack-parent" "$CURRENT"
echo "Stacked '$NEW' on '$CURRENT'"
echo ""
git stack-tree