Change the default shell of the user

    CLI Example:

    .. code-block:: bash

        salt '*' user.chshell foo /bin/zsh

def chshell(name, shell):
    '''
    Change the default shell of the user

    CLI Example:

    .. code-block:: bash

        salt '*' user.chshell foo /bin/zsh
    '''
    pre_info = info(name)
    if not pre_info:
        raise CommandExecutionError('User \'{0}\' does not exist'.format(name))
    if shell == pre_info['shell']:
        return True
    _dscl(
        ['/Users/{0}'.format(name), 'UserShell', pre_info['shell'], shell],
        ctype='change'
    )
    # dscl buffers changes, sleep 1 second before checking if new value
    # matches desired value
    time.sleep(1)
    return info(name).get('shell') == shell