December 9th, 2011· No changes.
October 19th, 2011· Allow comparison of DateTime objects against None.
October 19th, 2011· Reverted the single argument `None` special case handling for unpickling and continue to treat it as meaning `now`.
May 9th, 2011· Restored strftimeFormatter as a class.
· Added tests for read-only class attributes and interface.
February 11th, 2011· Changed testDayOfWeek test to be independent of OS locale.
July 29th, 2010· Launchpad #143269: Corrected the documentation for year value behavior when constructing a DateTime object with three numeric arguments.
· Launchpad #142521: Removed confusing special case in DateTime.__str__ where DateTime instances for midnight (e.g. '2010-07-27 00:00:00 US/Eastern') values would render only their date and nothing else.
July 12th, 2010· Fixed mapping of EDT (was -> 'GMT-0400', now 'GMT-4').
July 9th, 2010· Added EDT timezone support. Addresses bug #599856. [vangheem]
May 6th, 2010· Launchpad #572715: Relaxed pin on pytz, after applying a patch from Marius Gedminus which fixes the apparent API breakage.
April 30th, 2010· Removed an undeclared testing dependency on zope.testing.doctest in favor of the standard libraries doctest module.
· Added a maximum version requirement on pytz
March 4th, 2009· Launchpad #290254: Forward-ported fix for '_micros'-less pickles from the Zope 2.11 branch version.
February 3rd, 2009· Include all pytz zone names, not just "common" ones.
· Fix one fragile doctest, band-aid another.
· Fix for launchpad #267545: DateTime(DateTime()) should preserve the correct hour.