A nice explanation here: <a href="https:&#x2F;&#x2F;unix.stackexchange.com&#x2F;questions&#x2F;17903&#x2F;is-cal-broken-what-happened-in-september-1752" rel="nofollow">https:&#x2F;&#x2F;unix.stackexchange.com&#x2F;questions&#x2F;17903&#x2F;is-cal-broken...</a>