DST starts and ends a second late
Daylight Savings Time officially occurs at specified time such as
2:00:00 AM; meaning that there should be no time 2:00:00 AM, the
local time at the instant following 1:59:59 will be 3:00:00 AM.
GemStone does not begin applying the DST change until the second
following, which becomes 3:00:01. There is the equivalent problem
at the end of DST.
Note that bug #19449, DateTime creation on boundaries of Daylight
Savings Time, may complicate observation of this behavior.