Dissects a keyring credential lookup string from the supernova config file
    and returns the username/password combo

def pull_env_credential(env, param, value):
    """
    Dissects a keyring credential lookup string from the supernova config file
    and returns the username/password combo
    """
    rex = "USE_KEYRING\[([\x27\x22])(.*)\\1\]"

    # This is the old-style, per-environment keyring credential
    if value == "USE_KEYRING":
        username = utils.assemble_username(env, param)

    # This is the new-style, global keyring credential that can be applied
    # to multiple environments
    else:
        global_identifier = re.match(rex, value).group(2)
        username = utils.assemble_username('global', global_identifier)

    return (username, password_get(username))