What Time is It?

I was just doing a backup, and noticed that it seemed to be copying a lot files that hadn't changed -- in fact, pretty much every file.

A short while later, I worked out the problem. Using rsync under Cygwin on windows means that you are stuck with Window's idea of time. And Windows handling of daylight saving time is, well, broken. So, according to the operating system, the two copies of the files were different, since one was modified an hour later than the other.

There's no clean fix for this idiocy, but a simple solution (other than copying everything over again) is to set the rsync modify window to something more than an hour. For this application, the backup only happens once every few months, and so it is unlikely to cause a problem. But I'm glad I figure this out, rather than have to wait all night for the system to carefully change the file time of every file by exactly an hour...