Removes all branches that have been already merge into master.

git-cleanup-br.py

#!/usr/bin/env python
from sh import git

def main():
    print "before:"
    print git('br')

    for br in git('br', '--no-color'):
        br = br.strip()
        if "master" in br: continue
        git("br", "-d", br)

    print "now:"
    print git('br')


if __name__ == '__main__':
    main()