Use os.devnull when possible

CloudControl CLI

'''

import os

def git_version():

    global version

    import os

    try:

        os.chdir(os.path.dirname(sys.argv[0]))

        p = Popen(["git", "log", "--pretty=format:%H" ],

                  stdout=PIPE, stderr=open("/dev/null", "wb"))

                  stdout=PIPE, stderr=open(os.devnull, "wb"))

        p.wait()

        if p.returncode == 0:

            githash = p.stdout.readline().strip()