run pep8 on git pre-commit hook.

pre-commit-pep8.py

#!/usr/bin/env python
"""pre-commit-pep8.py
requirements

 - pep8==1.3.3
 - sh==1.07

in .git/hooks/pre-commit

    #!/bin/sh
    ./pre-commit-pep8.py

"""
import re
import sh
import sys

def main():
    for f in sh.git.diff(name_only=True, _tty_out=False):
        f = f.strip()
        if not re.search("\.py$", f):
            continue
        try:
            # pep8 --ignore=E501,E302  pre-commit-pep8.py
            sh.pep8(f, ignore="E501")
        except sh.ErrorReturnCode_1 as e:
            print "found the PEP8 errors."
            print e.stdout
            sys.exit(1)

if __name__ == '__main__':
    main()