[adbachman]

No joke, I actually hit this condition in a test suite and ended up stumbling across the October 1582 date in a Ruby library. It wasn't until I searched "October 10 1582" on the Web that I learned the significance. https://gist.github.com/abachman/f97806e1c0fe8e4e1849e5f8412...

tl;dr - MySQL uses 1000-01-01 as the minimum value for a datetime field. Different Ruby libraries use different methods to represent dates, which can lead to situations that appear to claim that 1000-01-01 != 1000-01-01.