make this executable in your .git/hooks/pre-commit to automatically update the branch name in your coveralls and travis badges

pre-commit

#!/usr/bin/python
import subprocess
import fileinput
import re

GITHUB_USER="" #enter your username
REPO=""        #enter the name of your repo

print "Starting pre-commit hook..."

BRANCH=subprocess.check_output(["git",
                                "rev-parse",
                                "--abbrev-ref",
                                "HEAD"]).strip()

# Output String with Variable substitution
travis="[![Build Status](https://travis-ci.org/{GITHUB_USER}/{REPO}.svg?branch={BRANCH})](https://travis-ci.org/{GITHUB_USER}/{REPO}) ".format(BRANCH=BRANCH, GITHUB_USER=GITHUB_USER, REPO=REPO)

coveralls = "[![Coverage Status](https://coveralls.io/repos/github/{GITHUB_USER}/{REPO}/badge.svg?branch={BRANCH})](https://coveralls.io/github/{GITHUB_USER}/{REPO}?branch={BRANCH})".format(BRANCH=BRANCH, GITHUB_USER=GITHUB_USER, REPO=REPO)

for line in fileinput.input("README.md", inplace=True):
    line = re.sub(r'\[\!\[Build Status\]\(https[^\)]*\)\]\(https[^\)]*\)', travis, line.rstrip())
    line = re.sub(r'\[\!\[Coverage Status\]\(https[^\)]*\)\]\(https[^\)]*\)', coveralls, line.rstrip())
    print(line)

subprocess.check_output(["git", "add", "README.md" ])

print "pre-commit hook complete."