From Derek’s post:
So the “correct” fix has the very negative impact of having all entries that publishers have used those settings to be off by an hour after updating to 2.1.1. Weighed in the balance, we’d rather have publishers continue watching dates closely on edit and working around this bug than we would suddenly breaking the dates for all of the entries on an entire site. So the fix for this issue is out until we can come up with a satisfactory way of determining not just what the date stored in the database is, but the intent the publisher had from when they edited the entry, and what settings they employed to achieve that. By reversing the old logic from those settings, we hope to bring those dates back to reality so that the simple correct fix to the problem works flawlessly.
In other words, manually change the dates when editing.