Git script to find parent branch of a branch

git-find-parent.sh

#!/bin/sh
#
# git-find-parent.sh
# Find the most likely parent branch for a given feature branch.
#

branch="$1"

# If no branch passed, use current branch
if [ -z "$branch" ]; then
  branch=$(git rev-parse --abbrev-ref HEAD)
fi

# Search local + remote branches except the branch itself
git for-each-ref --format='%(refname:short)' refs/heads/ refs/remotes/ \
  | grep -v "^$branch$" \
  | while read b; do
      base=$(git merge-base "$b" "$branch" 2>/dev/null) || continue
      [ -n "$base" ] && echo "$(git show -s --format='%ct %h %s' "$base") $b"
    done \
  | sort -n \
  | tail -n1 \
  | awk '{gsub(/^origin\//,"",$NF); print $NF}'