Issue #23718: Fixed parsing time in week 0 before Jan 1.  Original patch by
Tamás Bence Gedai.
diff --git a/Lib/test/test_strptime.py b/Lib/test/test_strptime.py
index a3ab426..3d24941 100644
--- a/Lib/test/test_strptime.py
+++ b/Lib/test/test_strptime.py
@@ -486,14 +486,14 @@
     def test_week_0(self):
         def check(value, format, *expected):
             self.assertEqual(_strptime._strptime_time(value, format)[:-1], expected)
-        check('2015 0 0', '%Y %U %w', 2014, 12, 28, 0, 0, 0, 6, -3)
+        check('2015 0 0', '%Y %U %w', 2014, 12, 28, 0, 0, 0, 6, 362)
         check('2015 0 0', '%Y %W %w', 2015, 1, 4, 0, 0, 0, 6, 4)
-        check('2015 0 1', '%Y %U %w', 2014, 12, 29, 0, 0, 0, 0, -2)
-        check('2015 0 1', '%Y %W %w', 2014, 12, 29, 0, 0, 0, 0, -2)
-        check('2015 0 2', '%Y %U %w', 2014, 12, 30, 0, 0, 0, 1, -1)
-        check('2015 0 2', '%Y %W %w', 2014, 12, 30, 0, 0, 0, 1, -1)
-        check('2015 0 3', '%Y %U %w', 2014, 12, 31, 0, 0, 0, 2, 0)
-        check('2015 0 3', '%Y %W %w', 2014, 12, 31, 0, 0, 0, 2, 0)
+        check('2015 0 1', '%Y %U %w', 2014, 12, 29, 0, 0, 0, 0, 363)
+        check('2015 0 1', '%Y %W %w', 2014, 12, 29, 0, 0, 0, 0, 363)
+        check('2015 0 2', '%Y %U %w', 2014, 12, 30, 0, 0, 0, 1, 364)
+        check('2015 0 2', '%Y %W %w', 2014, 12, 30, 0, 0, 0, 1, 364)
+        check('2015 0 3', '%Y %U %w', 2014, 12, 31, 0, 0, 0, 2, 365)
+        check('2015 0 3', '%Y %W %w', 2014, 12, 31, 0, 0, 0, 2, 365)
         check('2015 0 4', '%Y %U %w', 2015, 1, 1, 0, 0, 0, 3, 1)
         check('2015 0 4', '%Y %W %w', 2015, 1, 1, 0, 0, 0, 3, 1)
         check('2015 0 5', '%Y %U %w', 2015, 1, 2, 0, 0, 0, 4, 2)
@@ -501,6 +501,20 @@
         check('2015 0 6', '%Y %U %w', 2015, 1, 3, 0, 0, 0, 5, 3)
         check('2015 0 6', '%Y %W %w', 2015, 1, 3, 0, 0, 0, 5, 3)
 
+        check('2009 0 0', '%Y %U %w', 2008, 12, 28, 0, 0, 0, 6, 363)
+        check('2009 0 0', '%Y %W %w', 2009, 1, 4, 0, 0, 0, 6, 4)
+        check('2009 0 1', '%Y %U %w', 2008, 12, 29, 0, 0, 0, 0, 364)
+        check('2009 0 1', '%Y %W %w', 2008, 12, 29, 0, 0, 0, 0, 364)
+        check('2009 0 2', '%Y %U %w', 2008, 12, 30, 0, 0, 0, 1, 365)
+        check('2009 0 2', '%Y %W %w', 2008, 12, 30, 0, 0, 0, 1, 365)
+        check('2009 0 3', '%Y %U %w', 2008, 12, 31, 0, 0, 0, 2, 366)
+        check('2009 0 3', '%Y %W %w', 2008, 12, 31, 0, 0, 0, 2, 366)
+        check('2009 0 4', '%Y %U %w', 2009, 1, 1, 0, 0, 0, 3, 1)
+        check('2009 0 4', '%Y %W %w', 2009, 1, 1, 0, 0, 0, 3, 1)
+        check('2009 0 5', '%Y %U %w', 2009, 1, 2, 0, 0, 0, 4, 2)
+        check('2009 0 5', '%Y %W %w', 2009, 1, 2, 0, 0, 0, 4, 2)
+        check('2009 0 6', '%Y %U %w', 2009, 1, 3, 0, 0, 0, 5, 3)
+        check('2009 0 6', '%Y %W %w', 2009, 1, 3, 0, 0, 0, 5, 3)
 
 class CacheTests(unittest.TestCase):
     """Test that caching works properly."""