def config_get_regexp(key,
                      value_regex=None,
                      cwd=None,
                      user=None,
                      password=None,
                      ignore_retcode=False,
                      output_encoding=None,
                      **kwargs):
    r'''
    .. versionadded:: 2015.8.0

    Get the value of a key or keys in the git configuration file using regexes
    for more flexible matching. The return data is a dictionary mapping keys to
    lists of values matching the ``value_regex``. If no values match, an empty
    dictionary will be returned.

    key
        Regex on which key names will be matched

    value_regex
        If specified, return all values matching this regex. The return data
        will be a dictionary mapping keys to lists of values matching the
        regex.

        .. important::
            Only values matching the ``value_regex`` will be part of the return
            data. So, if ``key`` matches a multivar, then it is possible that
            not all of the values will be returned. To get all values set for a
            multivar, simply omit the ``value_regex`` argument.

    cwd
        The path to the git checkout

    global : False
        If ``True``, query the global git configuration. Otherwise, only the
        local git configuration will be queried.

    user
        User under which to run the git command. By default, the command is run
        by the user under which the minion is running.

    password
        Windows only. Required when specifying ``user``. This parameter will be
        ignored on non-Windows platforms.

      .. versionadded:: 2016.3.4

    ignore_retcode : False
        If ``True``, do not log an error to the minion log if the git command
        returns a nonzero exit status.

    output_encoding
        Use this option to specify which encoding to use to decode the output
        from any git commands which are run. This should not be needed in most
        cases.

        .. note::
            This should only be needed if the files in the repository were
            created with filenames using an encoding other than UTF-8 to handle
            Unicode characters.

        .. versionadded:: 2018.3.1

    CLI Examples:

    .. code-block:: bash

        # Matches any values for key 'foo.bar'
        salt myminion git.config_get_regexp /path/to/repo foo.bar
        # Matches any value starting with 'baz' set for key 'foo.bar'
        salt myminion git.config_get_regexp /path/to/repo foo.bar 'baz.*'
        # Matches any key starting with 'user.'
        salt myminion git.config_get_regexp '^user\.' global=True
    '''
    result = _config_getter('--get-regexp',
                            key,
                            value_regex=value_regex,
                            cwd=cwd,
                            user=user,
                            password=password,
                            ignore_retcode=ignore_retcode,
                            output_encoding=output_encoding,
                            **kwargs)

    # git config --get exits with retcode of 1 when key does not exist
    ret = {}
    if result['retcode'] == 1:
        return ret
    for line in result['stdout'].splitlines():
        try:
            param, value = line.split(None, 1)
        except ValueError:
            continue
        ret.setdefault(param, []).append(value)
    return ret