Index: Lib/imaplib.py
===================================================================
--- Lib/imaplib.py	(revision 88239)
+++ Lib/imaplib.py	(working copy)
@@ -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
@@ -1340,22 +1340,12 @@
         zone = -zone
 
     tt = (year, mon, day, hour, min, sec, -1, -1, -1)
+    utc = calendar.timegm(tt) - zone
 
-    utc = time.mktime(tt)
+    return time.localtime(utc)
 
-    # 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)
-
-
-
 def Int2AP(num):
 
     """Convert integer to A-P string representation."""
Index: Lib/test/test_imaplib.py
===================================================================
--- Lib/test/test_imaplib.py	(revision 88239)
+++ Lib/test/test_imaplib.py	(working copy)
@@ -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
Index: Lib/test/support.py
===================================================================
--- Lib/test/support.py	(revision 88239)
+++ Lib/test/support.py	(working copy)
@@ -38,7 +38,7 @@
     "check_warnings", "CleanImport", "EnvironmentVarGuard",
     "TransientResource", "captured_output", "captured_stdout",
     "time_out", "socket_peer_reset", "ioerror_peer_reset",
-    "run_with_locale", 'temp_umask', "transient_internet",
+    "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", "get_attribute",
@@ -945,6 +945,35 @@
     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.