`git-bring` brings upstream changes you care about to your local branches.

git-bring

#!/bin/zsh

CURRENT_BRANCH=$(git symbolic-ref HEAD 2>/dev/null | awk -F/ {'print $NF'})

can_ff() {
    a="$(git rev-parse "$1")" &&
    test "$(git merge-base "$a" "$2")" = "$a"
}

needs_sync(){
  a="$(git rev-list --max-count=1 "$1")" &&
  test "$(git rev-list --max-count=1 "$2")" != "$a"
}

git fetch --all
branches=()
eval "$(git for-each-ref --shell --format='branches+=(%(refname:short))' refs/heads/)"

for branch in "${branches[@]}"; do
    if (can_ff "$branch" "origin/$branch"); then
      if (needs_sync "$branch" "origin/$branch"); then
        echo "\n$branch can be fast-forwarded...."
        git checkout "$branch"
        git rebase "origin/$branch"
      else
        echo "\n$branch is already up-to-date."
      fi
    else
      echo "\nSkipping $branch..."
    fi
done

echo "\nReturning you to $CURRENT_BRANCH..."
git checkout "$CURRENT_BRANCH"