Bug #30454 'default_week_format' has no effect on YEARWEEK() as it has on WEEK()

Description:
While setting default_week_format has an effect on the function WEEK(), it does not have an effect on YEARWEEK() as one would expect.

For more info, see my comment on the documentation page 
http://dev.mysql.com/doc/refman/5.0/en/date-and-time-functions.html

How to repeat:
Execute the following line (2007-07-16 is a Monday):
mysql>SET default_week_format=0; select WEEK('2007-07-16'), YEARWEEK('2007-07-16'); SET default_week_format=1; select WEEK('2007-07-16'), YEARWEEK('2007-07-16');

Query OK, 0 rows affected (0.04 sec)

+--------------------+------------------------+
| WEEK('2007-07-16') | YEARWEEK('2007-07-16') |
+--------------------+------------------------+
|                 28 |                 200728 | 
+--------------------+------------------------+
1 row in set (0.04 sec)

Query OK, 0 rows affected (0.04 sec)

+--------------------+------------------------+
| WEEK('2007-07-16') | YEARWEEK('2007-07-16') |
+--------------------+------------------------+
|                 29 |                 200728 | 
+--------------------+------------------------+
1 row in set (0.03 sec)

Thank you for the bug report.

before pushing the fix for default_week_format affecting YEARWEEK(), please do disable YEARWEEK() function for partitioning, since it would not longer be deterministic. (Allowing YEARWEEK(<date>,<mode>) is OK, but not YEARWEEK(<date>)).

Marked bug#24956 as a duplicate of this.