#!/bin/sh -e
# git neck [-r] [COMMIT] - show commits until first branching point

[ "$1" = -r ] && shift && R=-r
COMMIT=$(git rev-parse --no-flags --default HEAD "$@")
# skip first elements of trail
TORSO=$(git trail $R $COMMIT | cut -d' ' -f2 | uniq | sed -n 2p)
# fall back to initial commit on empty trail
: ${TORSO:=$(git rev-list --max-parents=0 HEAD)}
git log --oneline $(git rev-parse --no-revs "$@") $COMMIT...$TORSO