[1.6.x] Fixed #21095 -- Documented new requirement for dates lookups.

Day, month, and week_day lookups now require time zone definitions in the database.

Backport of 9451d8d from master.

docs/ref/models/querysets.txt

@@ -2232,7 +2232,8 @@ SQL equivalent::
 (The exact SQL syntax varies for each database engine.)
 
 When :setting:`USE_TZ` is ``True``, datetime fields are converted to the
-current time zone before filtering.
+current time zone before filtering. This requires :ref:`time zone definitions
+in the database <database-time-zone-definitions>`.
 
 .. fieldlookup:: day
 
@@ -2255,7 +2256,8 @@ Note this will match any record with a pub_date on the third day of the month,
 such as January 3, July 3, etc.
 
 When :setting:`USE_TZ` is ``True``, datetime fields are converted to the
-current time zone before filtering.
+current time zone before filtering. This requires :ref:`time zone definitions
+in the database <database-time-zone-definitions>`.
 
 .. fieldlookup:: week_day
 
@@ -2279,7 +2281,8 @@ Note this will match any record with a ``pub_date`` that falls on a Monday (day
 are indexed with day 1 being Sunday and day 7 being Saturday.
 
 When :setting:`USE_TZ` is ``True``, datetime fields are converted to the
-current time zone before filtering.
+current time zone before filtering. This requires :ref:`time zone definitions
+in the database <database-time-zone-definitions>`.
 
 .. fieldlookup:: hour
 

docs/releases/1.6.txt

@@ -435,6 +435,21 @@ but will not be removed from Django until version 1.8.
 
 .. _recommendations in the Python documentation: http://docs.python.org/2/library/doctest.html#unittest-api
 
+Time zone-aware ``day``, ``month``, and ``week_day`` lookups
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Django 1.6 introduces time zone support for :lookup:`day`, :lookup:`month`,
+and :lookup:`week_day` lookups when :setting:`USE_TZ` is ``True``. These
+lookups were previously performed in UTC regardless of the current time zone.
+
+This requires :ref:`time zone definitions in the database
+<database-time-zone-definitions>`. If you're using SQLite, you must install
+pytz_. If you're using MySQL, you must install pytz_ and load the time zone
+tables with `mysql_tzinfo_to_sql`_.
+
+.. _pytz: http://pytz.sourceforge.net/
+.. _mysql_tzinfo_to_sql: http://dev.mysql.com/doc/refman/5.5/en/mysql-tzinfo-to-sql.html
+
 Addition of ``QuerySet.datetimes()``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~