Fixed #33879 -- Fixed wrong results for long intervals.

Added 10 hours to the month duration for intervals longer than 2 months.
Adding 10 hours directly to the constant would break other tests,
so the fix is added in the algorithm and only affects long intervals.

django/utils/timesince.py

@@ -88,6 +88,9 @@ def timesince(d, now=None, reversed=False, time_strings=None, depth=2):
         if count == 0:
             break
         result.append(avoid_wrapping(time_strings[name] % {"num": count}))
+        # prevent errors in long intervals
+        if name == "month" and count > 2:
+            seconds += 10 * 60 * 60
         since -= seconds * count
         current_depth += 1
         i += 1

tests/template_tests/filter_tests/test_timesince.py

@@ -147,6 +147,14 @@ class TimesinceTests(TimezoneTestCase):
         )
         self.assertEqual(output, "1\xa0day")
 
+    # Test for #33879 (wrong results for 11 months + several weeks)
+    @setup({"timesince19": "{{ earlier|timesince }}"})
+    def test_timesince19(self):
+        output = self.engine.render_to_string(
+            "timesince19", {"earlier": self.today - timedelta(days=358)}
+        )
+        self.assertEqual(output, "11\xa0months, 3\xa0weeks")
+
 
 class FunctionTests(SimpleTestCase):
     def test_since_now(self):