Clean repository after Pull Request has been successfully merged.

git_pr_clean.bash

#!/bin/bash

# Go to user-specified branch.
git checkout $1

# Get newest changes after PR merge.
git pull

# Update tracked remote branches.
git fetch --prune

# Delete all local branches that are already merged to master.
git branch --merged | egrep -v "(^\*|master|dev)" | xargs git branch -d