List all known patches in repos.

def _get_patches(installed_only=False):
    '''
    List all known patches in repos.
    '''
    patches = {}

    cmd = [_yum(), '--quiet', 'updateinfo', 'list', 'all']
    ret = __salt__['cmd.run_stdout'](
        cmd,
        python_shell=False
    )
    for line in salt.utils.itertools.split(ret, os.linesep):
        inst, advisory_id, sev, pkg = re.match(r'([i|\s]) ([^\s]+) +([^\s]+) +([^\s]+)',
                                               line).groups()
        if inst != 'i' and installed_only:
            continue
        patches[advisory_id] = {
            'installed': True if inst == 'i' else False,
            'summary': pkg
        }
    return patches