Note that this page was written in 2001; the leap second situation has gotten a lot more complicated since then, with far more diverging implementations that handle it differently, and no real momentum towards widespread adoption of software that handles them "correctly" (explicitly), like the localtime() "fix" preferred by DJB.
Most people seem to prefer ignoring leap seconds, pretending they don't exist by "smearing" them across the surrounding day, or even getting rid of them entirely. https://news.ycombinator.com/item?id=33658541 https://news.ycombinator.com/item?id=32226414