Show list of recently checked-out branches in reverse-chronological order

git-recently-checkout-branches.sh

#!/bin/bash
set -e

git reflog -n100 --pretty='%cr|%gs' --grep-reflog='checkout: moving' HEAD | {
  seen=":"
  git_dir="$(git rev-parse --git-dir)"
  while read line; do
    date="${line%%|*}"
    branch="${line##* }"
    if ! [[ $seen == *:"${branch}":* ]]; then
      seen="${seen}${branch}:"
      if [ -f "${git_dir}/refs/heads/${branch}" ]; then
        printf "%s\t%s\n" "$date" "$branch"
      fi
    fi
  done
}