Fixed #19210 -- Handling of leap years in django.utils.timesince

django.utils.timesince used to ignore leap years which lead to big
inaccuracies as soon as you used it on big time spans. This is the
most simple fix for this bug, as explained in the ticket.

django/utils/timesince.py

@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 
+import calendar
 import datetime
 
 from django.utils.html import avoid_wrapping
@@ -40,6 +41,10 @@ def timesince(d, now=None, reversed=False):
         now = datetime.datetime.now(utc if is_aware(d) else None)
 
     delta = (d - now) if reversed else (now - d)
+
+    # Deal with leapyears
+    delta -= datetime.timedelta(calendar.leapdays(d.year, now.year))
+
     # ignore microseconds
     since = delta.days * 24 * 60 * 60 + delta.seconds
     if since <= 0:

docs/releases/1.9.txt

@@ -285,6 +285,9 @@ Templates
   the ability to register libraries and builtins explicitly through the
   template :setting:`OPTIONS <TEMPLATES-OPTIONS>`.
 
+* The ``timesince`` and ``timeuntil`` filters were improved to deal with leap
+  years when given large time spans.
+
 Requests and Responses
 ^^^^^^^^^^^^^^^^^^^^^^
 

tests/utils_tests/test_timesince.py

@@ -131,3 +131,8 @@ def utcoffset(self, dt):
         self.assertEqual(timesince(future), '0\xa0minutes')
         past = datetime.datetime(1980, 1, 1, tzinfo=naive())
         self.assertEqual(timeuntil(past), '0\xa0minutes')
+
+    def test_thousand_years_ago(self):
+        now = datetime.datetime.now()
+        t = datetime.datetime(1007, 8, 14, 13, 46, 0)
+        self.assertEqual(timesince(t, self.t), '1000\xa0years')