Convert grouped short options like `-abc` to `-a, -b, -c`.

        This is necessary because we set ``allow_abbrev=False`` on the
        ``ArgumentParser`` in :prop:`self.arg_parser`. The argparse docs
        say ``allow_abbrev`` applies only to long options, but it also
        affects whether short options grouped behind a single dash will
        be parsed into multiple short options.

def expand_short_options(self, argv):
        """Convert grouped short options like `-abc` to `-a, -b, -c`.

        This is necessary because we set ``allow_abbrev=False`` on the
        ``ArgumentParser`` in :prop:`self.arg_parser`. The argparse docs
        say ``allow_abbrev`` applies only to long options, but it also
        affects whether short options grouped behind a single dash will
        be parsed into multiple short options.

        """
        new_argv = []
        for arg in argv:
            result = self.parse_multi_short_option(arg)
            new_argv.extend(result)
        return new_argv