前幾天 Twitter 伺服器的時間大爆炸，跳到 2015 年：
剛剛在 Hacker News Daily 上看到原因：「If you're using YYYY in your JVM service or %G in anything, fix it now」，原因是這樣：
The single character G instead of Y took down Twitter's API today.
If you're using YYYY in your JVM service or %G in anything, fix it now. You're very likely using the wrong year format.
Mon Dec 29 00:44:45 EST 2014
date -u "+%G"
ISO 8601 week numbering has 2015 start this week.
gslin@home [~] [01:22/W4] date
Wed Dec 31 01:27:00 CST 2014
gslin@home [~] [01:27/W4] date +%Y
gslin@home [~] [01:27/W4] date +%G
year of ISO week number (see %V); normally useful only with %V