diff -r 34af3e74292d Lib/imaplib.py
--- a/Lib/imaplib.py	Fri Apr 20 01:41:36 2012 +0200
+++ b/Lib/imaplib.py	Thu Apr 19 22:36:44 2012 -0700
@@ -22,7 +22,7 @@
 
 __version__ = "2.58"
 
-import binascii, errno, random, re, socket, subprocess, sys, time
+import binascii, errno, random, re, socket, subprocess, sys, time, calendar
 
 try:
     import ssl
@@ -1347,19 +1347,9 @@
         zone = -zone
 
     tt = (year, mon, day, hour, min, sec, -1, -1, -1)
+    utc = calendar.timegm(tt) - zone
 
-    utc = time.mktime(tt)
-
-    # Following is necessary because the time module has no 'mkgmtime'.
-    # 'mktime' assumes arg in local timezone, so adds timezone/altzone.
-
-    lt = time.localtime(utc)
-    if time.daylight and lt[-1]:
-        zone = zone + time.altzone
-    else:
-        zone = zone + time.timezone
-
-    return time.localtime(utc - zone)
+    return time.localtime(utc)
 
 
 
diff -r 34af3e74292d Lib/test/support.py
--- a/Lib/test/support.py	Fri Apr 20 01:41:36 2012 +0200
+++ b/Lib/test/support.py	Thu Apr 19 22:36:44 2012 -0700
@@ -50,7 +50,9 @@
     "findfile", "create_empty_file", "sortdict", "check_syntax_error", "open_urlresource",
     "check_warnings", "CleanImport", "EnvironmentVarGuard", "TransientResource",
     "captured_stdout", "captured_stdin", "captured_stderr", "time_out",
-    "socket_peer_reset", "ioerror_peer_reset", "run_with_locale", 'temp_umask',
+    "socket_peer_reset", "ioerror_peer_reset",
+    "run_with_locale", "run_with_tz",
+    'temp_umask',
     "transient_internet", "set_memlimit", "bigmemtest", "bigaddrspacetest",
     "BasicTestRunner", "run_unittest", "run_doctest", "threading_setup",
     "threading_cleanup", "reap_children", "cpython_only", "check_impl_detail",
@@ -1100,6 +1102,35 @@
     return decorator
 
 #=======================================================================
+# Decorator for running a function in a specific timezone, correctly
+# resetting it afterwards.
+
+def run_with_tz(tz):
+    def decorator(func):
+        def inner(*args, **kwds):
+            if 'TZ' in os.environ:
+                orig_tz = os.environ['TZ']
+            else:
+                orig_tz = None
+            os.environ['TZ'] = tz
+            time.tzset()
+
+            # now run the function, resetting the tz on exceptions
+            try:
+                return func(*args, **kwds)
+            finally:
+                if orig_tz == None:
+                    del os.environ['TZ']
+                else:
+                    os.environ['TZ'] = orig_tz
+                time.tzset()
+
+        inner.__name__ = func.__name__
+        inner.__doc__ = func.__doc__
+        return inner
+    return decorator
+
+#=======================================================================
 # Big-memory-test support. Separate from 'resources' because memory use
 # should be configurable.
 
diff -r 34af3e74292d Lib/test/test_imaplib.py
--- a/Lib/test/test_imaplib.py	Fri Apr 20 01:41:36 2012 +0200
+++ b/Lib/test/test_imaplib.py	Thu Apr 19 22:36:44 2012 -0700
@@ -11,7 +11,7 @@
 import time
 import calendar
 
-from test.support import reap_threads, verbose, transient_internet
+from test.support import reap_threads, verbose, transient_internet, run_with_tz
 import unittest
 
 try:
@@ -36,6 +36,13 @@
             b'25 (INTERNALDATE "31-Dec-1999 12:30:00 -1130")')
         self.assertEqual(time.mktime(tt), t0)
 
+    @run_with_tz('MST+07MDT,M4.1.0,M10.5.0')
+    def test_Internaldate2tuple_issue10941(self):
+        self.assertNotEqual(imaplib.Internaldate2tuple(
+            b'25 (INTERNALDATE "02-Apr-2000 02:30:00 +0000")'),
+                            imaplib.Internaldate2tuple(
+            b'25 (INTERNALDATE "02-Apr-2000 03:30:00 +0000")'))
+
     def test_that_Time2Internaldate_returns_a_result(self):
         # We can check only that it successfully produces a result,
         # not the correctness of the result itself, since the result