Comment 2 for bug 1187212

Auto-detecting sounds nice; in the default case (TZ's the same on web and DB), it's a no-op, but in the odd case, it just quietly handles the difference in the way the user would expect. A power user could still set a config option manually if they know better.

Using the GMT offset avoids all the issues with Mysql's known timezones differing from PHP's. Actual code: I had a quick look, and it's ugly, and I don't feel confident writing something to share with the world :)