Read both user configuration and local configuration.

def read_config(args, parser):
    """Read both user configuration and local configuration."""
    try:
        from configparser import ConfigParser as SafeConfigParser
        from configparser import Error
    except ImportError:
        from ConfigParser import SafeConfigParser
        from ConfigParser import Error

    config = SafeConfigParser()

    try:
        config.read(args.global_config)

        if not args.ignore_local_config:
            parent = tail = args.files and os.path.abspath(
                os.path.commonprefix(args.files))
            while tail:
                if config.read([os.path.join(parent, fn)
                                for fn in PROJECT_CONFIG]):
                    break
                (parent, tail) = os.path.split(parent)

        defaults = {}
        option_list = {o.dest: o.type or type(o.default)
                       for o in parser._actions}

        for section in ['pep8', 'pycodestyle', 'flake8']:
            if not config.has_section(section):
                continue
            for (k, _) in config.items(section):
                norm_opt = k.lstrip('-').replace('-', '_')
                if not option_list.get(norm_opt):
                    continue
                opt_type = option_list[norm_opt]
                if opt_type is int:
                    value = config.getint(section, k)
                elif opt_type is bool:
                    value = config.getboolean(section, k)
                else:
                    value = config.get(section, k)
                if args.verbose:
                    print("enable config: section={}, key={}, value={}".format(
                        section, k, value))
                defaults[norm_opt] = value

        parser.set_defaults(**defaults)
    except Error:
        # Ignore for now.
        pass

    return parser