The following code will print if you have any stashed code on a given branch. Add it to a repo's git/hooks/post-checkout to print whenever you change branch

stash_hook.sh

# print stashes that exist for the currently switched-to branch
GREEN='\033[0;32m'
NC='\033[0m' # No Color

branch=$(git rev-parse --abbrev-ref HEAD)
stashes=`git stash list | grep "WIP on $branch"`
if [ "$stashes" ]
then
  echo "${GREEN}You have the following stashes for this branch:"
  echo "${stashes}${NC}"
fi