24:00 12-31-1927. CLOCKS WENT BACK 5 min 52 sec and 1927 actually happened twice

I know Timezone are weird, but what does this mean? This appeared in an answer on StackOverflow by Jon Skeet, which can be found here: http://stackoverflow.com/questions/6841333/why-is-subtracting-these-two-times-in-1927-giving-a-strange-result/6841479#6841479