Merged the slinkp-datetime-200007 branch: fix the DateTime(anotherDateTime)...

Merged the slinkp-datetime-200007 branch: fix the DateTime(anotherDateTime) constructor to preserve timezones.

doc/CHANGES.txt

@@ -8,6 +8,9 @@ Zope Changes
 
     Bugs fixed
 
+      - Launchpad #200007: DateTime(anotherDateTime) now preserves the
+        timezone.
+
       - Launchpad #213311:  Handle "unsubscriptable object" errors
         during publishing traversal.
 

lib/python/DateTime/DateTime.py

@@ -704,12 +704,11 @@ class DateTime:
             if isinstance(arg, DateTime):
                 """ Construct a new DateTime instance from a given DateTime instance """
                 t = arg.timeTime()
-                lt = safelocaltime(t)
-                tz = self.localZone(lt)
+                tz = arg.timezone()
                 ms = (t - math.floor(t))
                 s,d = _calcSD(t)
-                yr,mo,dy,hr,mn,sc=lt[:6]
-                sc=sc+ms
+                yr,mo,dy,hr,mn,sc = gmtime(t)[:6]
+                sc = sc + ms
 
             elif isinstance(arg, (unicode, str)) and arg.lower() in self._tzinfo._zidx:
                 # Current time, to be displayed in specified timezone

lib/python/DateTime/tests/testDateTime.py

@@ -299,6 +299,19 @@ class DateTimeTests(unittest.TestCase):
         d = DateTime('1999/04/12')
         self.assertEqual(DateTime(d), d)
 
+    def testCopyConstructorPreservesTimezone(self):
+        # test for https://bugs.launchpad.net/zope2/+bug/200007
+        # This always worked in the local timezone, so we need at least
+        # two tests with different zones to be sure at least one of them
+        # is not local.
+        d = DateTime('2004/04/04')
+        self.assertEqual(DateTime(d).timezone(), d.timezone())
+        d2 = DateTime('2008/04/25 12:00:00 EST')
+        self.assertEqual(DateTime(d2).timezone(), d2.timezone())
+        d3 = DateTime('2008/04/25 12:00:00 PST')
+        self.assertEqual(DateTime(d3).timezone(), d3.timezone())
+
+
     def testRFC822(self):
         '''rfc822 conversion'''
         dt = DateTime('2002-05-02T08:00:00+00:00')